It's not that hard to find
I made it too
I had my Fundamental course at the Eridge estate in Tunbridge Wells. Had to take the international train from Rotterdam to Bruxelles, Eurostar to Ashford, and a train to TW.
At TW station I saw another guy who was wondering where he had to go, so I asked him if he was on the course aswell - he was. The group had to meet up at a small café / restaurant / pub like thingie - which had a car park - so we shared a taxi from TW station to the meet up point.
At the meet up point Lawrence, Alex & Dave showed up in with 2 Landy 's to transport us and our kit over some bumpy roads to the campsite.
On the way back I travelled with some people who had a transfer in London, and if IIRC that very train went to London ... Don't know what station though ...
I used this site to plan my journey, hope it is of some help for you aswell:
http://www.nationalrail.co.uk/
Have a great time at the course!! You'll love it to bits!!!
Don't forget to make some piccies to show us
EDIT:
I reckon you already read the articles by Chris in the article / review section?
http://www.bushcraftuk.com/content/articles.php?action=show&showarticle=53
http://www.bushcraftuk.com/content/articles.php?action=show&showarticle=23