Mickey,
If you are in the UK, and I assume by the web site for the Vertigo bike that you are, try Ribble and Wiggle to start, they both offer bikes like Tesco does. That is a low end bike, its components will be alright for a short while but it may not hold up well. Forget Craig's List in the UK, sorry about that one, my bad. and yes a 21" frame is pretty small for your size. Try to avoid department store bikes, they aren't assembled well and have a lot of corners cut as far as quality. I subscribe to Cycling Plus, from the UK, buy an issue of it or another road bike magazine and read up, them go to a few bike shops and maybe a local club that will work with you. Best of luck, you'll find the right bike.

Bill