I used these guys and there were very good. Looking at your questions they will be able to answer them over the phone:
Visa Medical Services
117a Harley Street
London W1G 6AT
Tel: 0207 224 2843
[email protected]
There really is no point in doing the visa process yourself as you will not get any direct exposure to either embassy or consulate officials sadly. The phone numbers are posted for show as they are never answered.