I don't know what you have over there in the UK, but I would probably check out Harrods in the electronics section, find a HT system you like, and then shop around for the best price. Since I'm not sure what speakers you have, you'd probably be better off to buy yourself a HT in a Box from Sony, JVC, Onkyo, Panasonic, etc.
I picked up my Onkyo 6.1 system (HT-S770) refurbished for a steal. Is it the best? No, but for under $1000, I believe it is one of the better HT-in-a-Box systems out there. You'll always get mixed reviews for every product. I'm picky and I like good sound, and the bass on this system is nice and tight, and really rocks. The speakers are also nice and crisp on the highs and mids, and I'm really happy with it. Sure, the speakers are bigger than your average home theater system, but you also get better sound out of them compared to the little 3" cube speakers that are in most home theater systems. Go shopping around, talk to some of the sound guys at sound shops around your place, and then just keep in mind that you'll have to by a USB sound card for your Mini.