Benjo,
The best advice I would give is to shop around and don't buy the first thing you see. I have just bought a new rig and my budget was about the same as yours.
I took a while deciding on a head - shortlisted it to a few - Warwick ProFet 5.1, Ashdown Mag600 and Peavey Tour 700 (or possible 450).
All in the same-ish price range all roughly the same spec. In the end, I went for the Warwick - heard nothing but good things about their customer service, good reliability and osund (for the price).
I had heard about some reliability with Ashdown heads (and mine WILL get punished on tour) and have never been totally convinced by them - lookswise and soundwise on lower range ones.
Also, my last rig was Peavey and wasn't really fantastic sound wise. It was more of just a "noise generator" really - no noticeable tone to it. BUT - if you want something to be LOUD, solid and long-living, then I can't see them being beaten.
Anyway, mini review over - I managed to get an ex-demo Warwick Profet 5.1 head for £199. Only a couple of small scratches on the top of the case, but I have rack mounted it anyway, so I doubt I will see them again...
I have also got on order a Warwick 6x10 cab. Probably a bit too big for your needs, but at £385 brand new and with the spec on it, it will be great for me.
For what you say you need, something around this size will probably be more than enough.
(Finally - a quick heads up. If you do fancy Warwick gear, I got the head from www.soundunlimited.co.uk. The guy said they are going to stop stocking Warwick gear, so will be having a sale on it all pretty soon - may be worth keeping an eye on. Or give them a ring...)
And by the way, I don't work for them, I just got a real good bargain and there might be something there to help you out.
Sorry to ramble, but I hope this helps.
Rhymes