Well, yes and no. I meant no choice as there is generally only one long-term carpark on the airport. There are ones run as small businesses further out (sometimes up to about 15 miles away) but they're not very convenient.

As for public transport; getting to heathrow from here is an hour on the train to london then another hour (at least) on the tube. Changing train is a pain with luggage. There is a coach that goes direct, but that can take between 2-4 hours, depending on how the M25 (the dreaded london orbital) is feeling on the day. Not ideal for catching a flight, but fine for the way home!

Hugo