Since I bought my unit off ebay it came with American maps, I need European maps (in particular UK) where can I get these from, how much and also will the American unit work with UK maps?

I'm guessing you're referring to a D3, not a D2 or D1, but here's all the info you'll need:

http://www.avic411.com/forum/viewtopic.php?t=11065&highlight=europe

http://www.avic411.com/forum/viewtopic.php?t=10938&highlight=europe

http://www.avic411.com/forum/viewtopic.php?t=8987&highlight=europe

http://www.avic411.com/forum/viewtopic.php?t=10582&highlight=europe

http://www.avic411.com/forum/viewtopic.php?t=10186&highlight=europe

http://www.avic411.com/forum/viewtopic.php?t=3293&highlight=europe