You could probably try getting started by reaching out to some EU-focused angel investors - there's quite a few in london.

I keep a list on Twitter with a few who are active: http://twitter.com/#!/list/f/eu-angels There's also AngelList for Europe here: http://angel.co/europe

There are also other options. Since you're aiming for 20k, which is not a high amount, you may want to try the 3 f's first - Friends, Family, Fools. A personal loan might work too. It boils down to how much risk you're willing to take. (I'd go with angels first, because investing is what they do and they can help you more than just providing you with cash.)