Yes - they have a warehouse in Berlin supplying Germany, France and the UK.
3 - 5 day delivery to the UK.
Their more popular kits frequently go out of stock, so you might have to wait a bit.
They also sell through Amazon UK (and possibly
ebay?).
Yosepower will be fine for someone who has done a conversion before and is converting a fairly standard bike (square taper BB, V brakes etc.).
For a newbie or for a more modern up-market bike I still recommend paying the bit extra and going to Woosh - they are just so helpful.
I'm getting ready to transfer my existing Woosh kit to another bike - although I only need £25 worth of bits to complete the changeover Woosh are just as helpful as if I was spending £500.