Lots of people use CafePress, but I don't know if they have a spot in the UK. Why not call local screen printers and see if you can work out a good deal. Then you will save on shipping. Single color designs will be the cheapest to produce.
hey :-) u answered my question about me singing. iu need a full keyboard to do the music notes, and then u do alt and then hit 1 and 3 really fast. at least thats what i heard. i have a laptop and just do copy and paste