How to pay a deposit to a campsite in Germany?

Hi,

I have booked a pitch on a site in Koblenz during August and they are asking for a 50E deposit to be paid into their bank account.  I have never done this before and wonder if there is a quick and cost effective way of doing this?  I bank with Santander and use internet banking but don't think I can make a transfer out of the UK.

Any tips welcome please.