Its really hard to say what UK planes will be like after all the CV nations have been properly balanced. As it stands right now, it really depends on what you define as "worth it".
If you have a UK BB line, then a UK CV wouldn't be a bad idea, since some of the crew, like gunners and supports could be used on your CV as well. This would also provide you with additional credits you will eventually need for a BB6.
As stated above, UK CVs are great if you really like using torp bombers. The UK fighters aren't really any good, but provided you are using good pilots (elites, vetted, etc.) they will hold their own. Just don't expect to get as many plane kills in fighter vs. fighters as you would with KM or US. The UK dive bombers are usable, but again, don't expect the same effectiveness as you would from other nations.
If you don't have (or plan to have in the near future) a UK BB, you don't have a particular desire to use torp bombers a lot, or you don't have money to spend on making your pilots good, then I would suggest using another nation that is more well rounded.
I personally like my UK CV, but at the end of the grind I wish I had spent more time on another nation CV line.