Arrive Heathrow on Tuesday at about 13:00. Rick Steve's book says we should see Bath. We'd like to see Stonehenge/Salisbury also. Need to be in Dover by mid day on Friday. Is this even doable. How to get there from where?
You could take the bus from Heathrow to Bath. We did in April and it worked great our plane was late and they only charged a change fee less that ten GBP. Train to Salisbury then on the Dover. Stonehenge might be more of a challenge but there is a shuttle bus for a fee. I don't know whether I would recommend scaling the learning curve to drive for such a short period. We always rent through Autoeurope, with whom the bets deals are for a full week rental. There may be better deals for shorter periods through other means. Neither Bath nor Salisbury is an easy town to park in though. Set aside a full half day for Salisbury Cathedral, and take the tour that goes up into the rafters and tower. I also highly recommend the Roman Baths in Bath (of course, far and away the best sight in town), along with Dover castle. I love castles and that was an especially good one.
It's a bit of a rush, but I'd suggest the following: Tuesday - Heathrow to Bath either by National Express coach or train (which involves going into London and travelling from Paddington station). Arrive Bath mid/late afternoon. Wednesday - all day in Bath Thursday - depart Bath in the morning. The train to Salisbury takes an hour or less. Tour to Stonehenge from here. Overnight Salisbury Friday - get the 08.15 train from Salisbury to London Waterloo, arriving 09.51. Go up the escalators from the concourse at Waterloo and follow the signs to Waterloo East. Catch the 10.13 from Waterloo East to Dover Priory, arriving 12.02. There are faster trains to Dover from St. Pancras, but you will already be at Waterloo and it's 5 minutes walk, all indoors, to Waterloo East.
If arriving at Terminal 5 take the Railair coach to Reading and pick the train up there. This is quicker and cheaper than taking the train into London and back out again. The coach option requires travelling backwards to LHR central bus station.
Thank you to all three of you. You've all given great hints to do what I've been trying to sketch out in my mind!
Sheryl, you have plenty of time to do what you propose. You do not mention means of transport, whereas all have assumed public transport. You have also not mentioned the reason for mid day Friday arrival in Dover. VS mentioned Dover Castle, which I found the most interesting of all the places mentioned. If you are catching a ferry to France, I would arrive in Dover Thursday and spend at least a few hours at Dover Castle. If you are planning to spend Friday afternoon at the castle rather than a ferry, I would follow the advise to Bath. I would visit the baths and cathedral on Tuesday and take the morning walk on Wednesday. Rent a car and drive to Stonehenge and Salisbury, continuing on to Brighton. Stay in Brighton and tour the Royal Pavilion Thursday morning and then drive by Beachy Head to Dover on Thursday. Tour the castle on Friday morning.