Oh. One more thing: now is actually a very good time to buy a bike. The 2012 models are coming in, so shops are discounting the 2011 models, which often are no different apart from colour. As an example: the 2011 Trek 7.3FX with rim brakes is available from Evans for £425, down from £500. The disc brake model is £490 down from £550, but only available in limited sizes.
Which reminds me: do make sure you get a bike in a size that's appropriate for you. Unfortunately, many shops will sell you whatever size they have on the shop floor, rather than the one you need. If you go to a larger shop like Evans, you can check the availability of the different sizes online. If they don't have your size at the local shop, you should be able to have one sent down from the warehouse.