Wheel size of 26 is standard. I am slightly shorter than you but have two 17-inch frame bikes (Konas, beautiful things).
As snags says, can you stand over the frame? If you have to brake suddenly and slide off the saddle, will you squash your precious bits on the crossbar?
Buy a bike from a decent shop, they will let you try them out before you buy. Also, like anything else inlife, you get what you pay for. If you pay �200 in Halfords that's what you'll get. Spend a bit more, say �500, and cycling will become a joy. Spend �2000 on a really top-end Kona or Specialized and you will consider giving up driving.