Newbie needs your opinion... which bike?

Hello all,

I currently ride a battered old Claud Butler Urban 200 - had it for 5 years and it has been OK, no complaints.

I rarely use the gears on my Urban 200 so I now want to experience a single speed bike and in the process hopefully get a little bit fitter. I am complete entry level for single-speed, but would like the bike to give me the option of fixing so it would need a flip-flop hub.

I have about £500 to spend through our work Cyclescheme, so second-hand bikes are not an option, the scheme only allows for new bikes.

Which bike would you recommend for me to try for a test ride? I would like something that is fast, safe, easy to handle and robust as it will be used for commuting daily. I am a female, 5 foot 8 inches, medium build - if that make a difference.

Cheers! :)

Surly Steamroller, 53cm, has a flip flop. Will need to add a freewheel cog (£10) - the bike is listed as £600 at Evans Cycles, but can be had for £540 from www.winstanleysbikes.co.uk (they deliver for free) OR Evans will price match the £540 - that's about £500 :0)