As a fellow newbie

I'd go to your local bike shop and ask around to see what they recommend for your needs / ability / budget.
Road Racer / Hybrid / Mountain Bike ?
The important point rather than which bike is making sure you get one that fits as there are marked differences in each manufacturer and frame size as I found out - medium in one brand is not necessarily medium in another!
At this point you'll have a bike that is your starting point - then go out and compare other brands etc. to see which feels better for you and ticks your boxes.
You'll need to allow a couple of hundred for accessories and as a newbie you might be better looking towards the £500 end of your budget - you can always upgrade later if the bug bites!