ah Halfords - where to start???
Kwiter - in your price bracket and ability, then I can see Halfords being a possibility but for those with slightly more serious tendencies with the bike, then it's like going to Sportsworld for your running gear - you wouldn't!
the staff are usually spotty oiks who know nothing technical, and their bikes are, frankly, cheap end of the market tat
£200 at your local bike shop is still very cheap - nowhere near expensive - but I think you'd get better service and support there...........
once you get into more serious biking then anything below £500 is cheap, £500-£1000 is OK, £1000-£2000 is good, £2k-£4K is serious, £4K + is pro or you have money to burn..........