If there is nothing actually wrong with your camera and you just want it checked over there are several "official" Canon repair centres and the Canon UK facility in Elstree.
You can find all the addresses on the canon UK website, look under service for DSLR's
There is also a PDF there somewhere with likely service/repair costs.
With regard to is it worth it - for a 50D - and in the absence of any obvious problems, then no I would not bother.
HTH
David