Daniels & Associates Inc., a Denver cable television concern, has agreed in principle to merge with United Artists Communications Inc. The proposal calls for stockholders of Daniels to get $108 million in cash and $82 million in convertible preferred stock of United Artists for their stock. Under the agreement, Daniels will become a wholly owned subsidiary of United Artists. The merger with Daniels will expand United Artists' cable holdings to cover about 1.2 million cable subscribers in 26 states. The deal is expected to close in June, subject to obtaining the necessary clearance.