Hi,
I rented a Honda Hornet from GDK in Gland (
http://www.gdkmotos.ch/fr/index.html) when I first started to learn. It was quit pricey... 1000CHF for a month but it included all the insurance etc that I needed. That was in 2009.
I don't know about going to the UK and back though. As I had an 'L' plate I wasn't permitted to use a bike outside of Switzerland.
Let us know ho you get on.
Mace