The important thing is to get the correct size when buying road bike. I suggest you go to good local bike shop. They should advise you and should offer to help you adjust it to fit such as changing the length of the stem which connects the frame to the handle bars. You should then think about the quality of the frame as you can always upgrade other stuff as it gets older. A good quality light alloy frame from someone like Trek or Specialized would be a start, you may even find a bike second hand if you know what you want or the bike shop may have one they have taken in part-exchange. Try and join a local club that caters for novices if you want find someone to ride with. Finally don't forget your safety - helmet, gloves etc