Why would he only be able to buy an AV amplifier? Floorstanders don't always make up the fronts either.
If you're hell bent on a surround setup, then do buy an AV amp, but only buy 2 speakers to start with. Even then I'd probably be leaning towards just getting a stereo amp, as you can easily use this in conjunction with an AV amp at a later date.
If you're willing to look at second hand goods, then steer clear of these flashing light dixons type systems and look at proper hi-fi gear. Ignore watt ratings and look at something like the Sonic T amp.
http://cgi.ebay.co.uk/SONIC-IMPACT-...9732872359QQcategoryZ3280QQrdZ1QQcmdZViewItem
They're very capable little amps which for a small room setup would be perfect.
The Cambridge Audio A5 is also another favourite budget amp, new or used.
http://cgi.ebay.co.uk/Cambridge-Aud...9731155065QQcategoryZ3280QQrdZ1QQcmdZViewItem
They can be bought new at richer sounds pretty cheaply so it would be worth looking there too.
My brother has this Denon amp, and it's a good unit, driving my large floorstanders well considering its price.
http://cgi.ebay.co.uk/Denon-PMA-255...9730956682QQcategoryZ3280QQrdZ1QQcmdZViewItem
A nice NAD amp there too:
http://cgi.ebay.co.uk/NAD-3020i-Cla...9731188244QQcategoryZ3280QQrdZ1QQcmdZViewItem
Bear in mind these are all stereo only amps, but they can be integrated into a surround sound setup at a later date easily.
Watch this amp:
http://cgi.ebay.co.uk/POWERFUL-DENO...9733256404QQcategoryZ3280QQrdZ1QQcmdZViewItem
It's enormous, and despite its age is very capable indeed. I'm not sure quite how much it'll rise to, but you never know, you might get a bargain. This was once a top of the line AV amp costing thousands of pounds.
One important consideration is that even though these AV amps might be 2-7 years old, they wil still do more than you'll ever need.
I can't see anything good on
www.avforums.com, but that's normally a great place to pick up second hand bargains.
Spend £100 on speakers and £100 on amp or thereabouts. Speakers are easily found, and any of the major manufacturers will fit the bill. I'd be looking at bookshelf designs rather than floorstanders at this stage. Look at things by Mission, KEF, Wharfedale, Tannoy, MS, Celestion or B&W. If it looks good, and is in good condition then they'll probably sound ok. If they've not been looked after then it'll be pretty obvious.
I hope I've given you a few ideas, a good place to start would be to go to richer sounds and have alisten to some things and look around the shop.