I'm currently looking for a decent 30/50 watt amp head, good for modern rock sort of stuff. I have a budget of £600/£700. The other guitarist in my band uses a Orange Rocker 30 so i'm looking for something which could be a nice contrast to that. I'm pretty stumped so any suggestions would be much appreciated ...

inoceans.bandcamp.com <<< This is what my band sounds like, just to get a rough idea of what sort of sound im looking for.

Check out the blackstar ht club 50. I think that would be a good amp for what you are looking for.
Godin Icon Type 2 Classic
Vox SDC 33
Mesa Boogie Express 5:50 2x12
Roland Cube 80XL
Boss Tuner
BBE Boosta Grande
Ibanez TS9 Tube Screamer
Amptweaker Tightmetal
ISP Decimator
Zoom G3
TC Electronic Flashback
Visual Sound H2O
Tom will hook you up nice and good like. PM him.
Gibson Les Paul Studio
Highway One Telecaster
Dean Evo
Mesa F-50
Laney GH50L
Vox AC30 C2
Ampeg V2