This is probably what I'd be looking at
http://www.pedalon.co.uk/acatalog/giant_scr_20.html
Alloy frame, with carbon fork, so you get a comfy ride and the bike will be responsive, the group set is reasonable so if you start taking things a bit more seriously the bike will still do what you want it to.
But if you want to go clipless pedals, which you oughta think about as it makes pedalling more efficent that'll be extra cash.
Or this, which might be more on your budget, frame set isnt as good, neither are the components, but it leaves you more room to spend on shoes and bits and pieces in your budget.
http://www.wiggle.co.uk/ProductDetai...%20Road%20Bike