Hi Glenn,  Your best bet would probably be to stay in Blandford itself,
as it is the nearest sizeable town.  There is a bus service, operated by
Wilts and Dorset Bus Company, which takes you from Blandford right past
the rally site.  It is service No. 184, which is basically a Weymouth to
Salisbury service.  I have seen the bus running when I've visited the
rally, but never used it.

I am reliably informed that the drivers will stop opposite the rally
site entrance on request (ask for a ticket to Tarrant Hinton when
boarding to get the right fare I should think).  Frequency is not bad,
the first sensible departure is at 09:14 from Blandford, gets you to
the rally site for 09:39.  Getting back also not a problem, bus at
18:24 or 20:24.  If you want to look at the full timetable go to:
http://www.wdbus.co.uk/htm/ttSouthern/184-185.pdf

Of course, once upon a time you could have caught a train right into
Blandford town, or possibly even better, 'Stourpaine & Durweston Halt'
on the old Somerset and Dorset Joint Railway, but thanks to Dr Beeching
and the 1960's railway closures, that's no longer an option!

The nearest (easiest) station to Blandford is Salisbury, and it's easy
to get from there to Blandford using the same bus service as above.  If
you're arriving at Heathrow, it's a little tricky, you need to get from
Heathrow to Reading on the express coach, then Reading to Basingstoke
on a local train service, and finally a train from Basingstoke direct
to Salisbury.  All of those have frequent services however (2 an hour).
London Waterloo station has direct services to Salisbury (2 an hour).
Find any train times at http://www.nationalrail.co.uk/planmyjourney/

Hope you enjoy your visit!

Nicholas Newble