Q : At 55, I keep up with fashion trends but am more interested in creating my own style . Right now I'm enjoying the revival of turtleneck sweaters because they cover my neck. But what do I do when warm weather arrives? --P.N. A: Sleeveless turtleneck sweaters will be a big item in the stores this March, as they were featured in the spring ready-to-wear openings by designers in Milan, Paris, London, New York and Los Angeles. It's all part of a '50s revival, starring all the clothes Grace Kelly used to wear--including the scarf illustrated here. The spring sweaters are made of cotton as well as viscose and rayon, so they'll be practical on all but the steamiest days. And if your arms are not firm enough to be bared, wear your sleeveless turtleneck with a lightweight jacket made of cotton, linen or rayon--the three coolest fabrics. Or follow Kelly's lead and throw a sweater over your shoulders. Q : I have an old but very fine French baby alligator purse. I understand that these last forever but need to be redyed and reglazed from time to time. Do you know of a leather worker who would be qualified to handle this kind of problem? I have asked at every store, every shoe-repair shop and every other place I could think of--to no avail.--K.M. A: Jacob's Leather Goods, formerly Kurt Chambre, at 8406 West 3rd St., Los Angeles 90048, specializes in just such projects. Chambre says that only black alligator and white alligator should be dyed, explaining that the natural highlights of the skin--the very markings that would be covered--would be ruined by being dyed any other shade. For brown and other colors he recommends glazing with clear lacquer. For black, he glazes in black lacquer, thereby dyeing in the process. For white, he uses a white-lacquer glaze. Prices range from $15 to $25 per bag. Allow two weeks. Q : I'm planning to make my daughter's wedding dress. Can you please help me find a book or pamphlet with hints or shortcuts? -- O.P. A: "Sew a Beautiful Wedding," by Gail Brown and Karen Dillon, is priced at $6.95 and can be ordered through Palmer / Pletsch Associates, P.O. Box 12046, Portland, Ore. 97212-0046. Add $1 for postage and handling, and allow four to six weeks for delivery. This book contains 128 pages of bridal how-tos, from sewing the gown and wedding accessories to tips for choosing the most flattering style. It also tells you how to sew specialty fabrics such as lace, velvet, satin and sheers. You might also want to contact Bridal Elegance, 1176 Northport Drive, Columbus, Ohio 43220, a company that offers patterns for parts of gowns that can be mixed or matched in constructing your own look. Most patterns sell for between $6 and $9. And Past Patterns, P.O. Box 7587, Grand Rapids, Mich. 49510, offers authentic patterns for wedding gowns from 1885, 1893, 1907, 1931 and 1939. Some come with information on where to buy supplies such as Belgian lace collars and cuffs. In an effort to assure the proper silhouette for those period styles, the company also has a corset pattern available in sizes 10 through 20. Its catalogue is $5, including postage and handling. Q : Some time ago, you wrote about a company that would cover your shoes in the same fabric as your dress or suit. The price was beyond my means. Since that idea has become fashionable, does anyone offer the service at more affordable prices?--V.L. A: You can cover your own shoes to match your clothes if you follow the directions offered by Border Beautiful, 11101 Crestview Blvd., Kokomo, Ind. 46901. Ruth Tomlinson, who developed the pattern, says that an experienced craftsperson can complete the project in about two hours--an hour for each shoe. "Perfectionists take a little longer," she adds. Simple pumps take less time than shoes that are heelless or toeless. The pattern costs $3 and consists of a three-page set of instructions with diagrams. Q : Years ago, sheer dresses came lined or with matching slips. Now it is difficult to find lined dresses at a reasonable price and impossible to find slips that match. What is the alternative?--D.A. A: Beige or nude-colored slips are the ideal underpinnings for sheer pastel dresses, and black slips work with dark see-throughs. Your question is pertinent right now, because more pastel dresses are being shown for spring and summer, 1986, than have been in many years. Q : My dad is 94 years old, and for the last few years he has worn a London Fog zipper jacket with a fur collar. It still looks brand - new, but it's a little tight around the waistline. I took it to the cleaners, and the alterations woman said that she couldn't do a thing. Can you help?--F.B. A: Try to find a rib-knit fabric to match the color of your dad's jacket, and ask a seamstress to insert gussets at each side seam. If you can't find a color match, use a complementary shade--such as a brown rib knit with a beige jacket. Q: What is the difference between braces and suspenders?--R.N. A: Braces is the British term for suspenders. According to "Esquire's Encyclopedia of 20th Century Men's Fashions," the two words were used interchangeably in this country until the early 1900s, when Sears, Roebuck & Co. started to differentiate, reserving the word braces for the devices used to correct posture. Q: Please tell John Sullivan of American Silk Mills that the fabrics he recommended for use in restoring old quilts and antique clothes are far too heavy for those needs. The reader is looking for the fabric Crepeline. It's a silk chiffon available from a New York company called Talas. I teach textiles and have used the fabric for years. So do the people in the Los Angeles County Museum of Art's textile conservation department.--D.K. A: Elaine Haas of Talas, 213 W. 35th St., New York, N.Y. 10001-1996, says that Crepeline is a French fabric sized to give it body and resembles fabric used for wedding veils. Many museums and textile restorers use it to strengthen fragile gowns, she says, and her firm has also sent Crepeline to the White House, where it's used to keep dust off of draperies and furniture. Crepeline, at 39 inches wide, comes in natural at $9.25 a yard, brown at $9.45 a yard and black at $10.15. Add $3 for postage and handling for orders of one to three yards. If you'd like larger quantities, write for postage prices. Q: I'm trying to find a one-piece thermal undergarment that looks like a long-sleeved dress. The reason? I prefer to wear dresses to work, but my office is very cold. Does anyone make such a garment?--A.S. A: You might try Tee-PJ's, T-shirts that end just above the knees and are available with short or long sleeves. The fabric is a mid-weight 100% cotton knit. They're meant for sleeping, but there's no reason you couldn't wake them up for duty as underdresses. The long-sleeved version, in sizes small through extra large, is about $15 in white or soft blue. To order, write to Wittmann Textiles, Drawer A, Hobe Sound, Fl. 33455.