London is a great place to hobby.
I traveled there many times and now I'm a resident.
Never had a problem and have never been disappointed.
As Valerie said, there are many great agencies.
Still want to do your homework.
Try www.Captain69.co.uk
I've never paid in any currency other than pound sterling.
Have fun, London is an incredible city.
Pay for a month membership and cancel. It is worth the £15 (I believe that is the price)