If I had 1200 to spend on a FS it would be a Boardman Team, and I'm a dedicated, card carrying, committed bike snob. You simply will not find better for the money. Any other brand and you will find compromises in component choice that will irritate you until you can afford to upgrade. Buy it mail order and build it yourself if the
Halfords spannermen trouble you.
Otherwise I would buy a Cube HT or a Genesis HT.
Alternatively, buy a used frame and build it up with
Ebay bargains. A giant Trance frame off ebay for about 500 quid and the rest is down to you, your internet trawling power and paypal account.