Arrive 08-12-2011 London heathrow airport and want to travel to St Andrews air/rail/bus stay 3 days and return to Bristol
I don't see a question mark anywhere in your post (or other punctuation). What is the specific question, please?
What is the best /most economical way to get from Heathrow Airport to St Andrews and back to Bristol ?
Heathrow-St Andrews: Fastest would be to fly directly from LHR to Edinburgh on either British Airways or BMI, take the train to Leuchars (the closest station to St Andrews), and take the bus from there to St Andrews. St Andrews-Bristol: Fastest would be to take the bus to Leuchars, take the train to Edinburgh, and take a direct flight from there to Bristol on easyJet.