How tall and heavy are you Pete? It does matter
And for the record, the Halfords bikes are most excellent on spec and do in fact get very good reviews now.
Last week it was 20% off Halfords bikes, the Kraken came in at £329.99, that is ridiculously cheap for the spec you get and the Fury is also a great bike for the money, and i would have most certainly bought one if they could cater for my size i.e. 22" frame, their frames only goto 20".
Failing that and depending on your budget, depending how "brand conscious" you are. You could try Mongoose or Giant, both are great bikes but you dont pay for the name.
The Giant Terrago is a good starter bike, you can find it for £350 online, but you should goto the store and try it first, i considered this bike also but no local stores had my size in stock of any of the Giant bikes so i could not try it out.
The Mongoose Amasa Elite 2008 is a good bike, superseded by the Tyax Super, is also a great bike for the money.
I considered all these but in the end i made the decision to purchase the bike local, i.e. f**k sending parts off to mail order/ online store when they go wrong etc, + you can work out deals with your local store, push for discount or bundled items.
Personally i looked around 10 bikes shops and finally purchased from the shop that didnt try to upsell, or push me to one of their dealer specific brands over other cycles i had expressed interest in. In the end i found a local store who gave me several options and had many bikes in stock in my size which really helped in my impulse decision to purchase a bike i had not even considered.