Just to throw in another wild card....
If you can find one - a FAS AP604 is a good compromise...
Manufacturers details here...
http://www.dominoguns.it/catalogo/?p...ria-compressa-

Its as light as a gamo compact, significantly easier to cock (same overlever method) and has a massively better trigger and grip.
Its very well made too - no plastic anywhere.
I've owned both and the FAS will easily outshoot you for quite a few years while you save up for something better.

BAR were selling them new at one point, but typically S/H they go at about the £150-200 mark

However, they are not so easy to find - but you could try a wanted ad.