Here is a link to the list of UK Panel Doctors you can use for a medical. It is worth phoning around a few as prices can vary a lot (we went to Southampton rather than Devon and saved £130 which paid for weekend away :lol: ) and we were cheeky and asked if there was a discount for cash so saved another 10%!!
Cannot recommend Dr Goodall at Southampton enough :D Excellent and great with kids.
Forms for medicals are available online - 160 & 26
If you are completing your visa application online you will be able to log in and download the medical forms with your details completed once you have a TR number.