I found a fantastic option for the marathon this year and will be staying at the same place again next year.
There is a (small private) school called All Saints in Blackheath (almost ON the heath) where the parents operate a b&b system the night before the marathon. You can stay for £40 b&b or £50 includes a pasta party the night before in the school hall. It was fantastic, there was a choice of 5 homemade dishes along with various salads, cous cous, anything you want to drink and ample choice of deserts. We really were waited on by some lovely people.
We ended up staying with the local vicar and his family (son went to the school). They were SO hospitable. The minute we walked in they offered my hubby a beer and he sat watching the footie with the vicar! They check in advance what you would like for breakfast and do their best to make you comfortable.
I literally woke up at 7am hearing the helicopters overhead broadcasting on the local radio. We were no more than 3 mins from Blackheath itself.
Also, for first timers, you put your posessions in a large red bag and meet them again at the finish so no need to worry aboutleaving them at the hotel. Hubby and I made sure we travelled lightly as he was trying to see me at various points around the course.
Anyway, the lady who deals with this is called Phillippa. She can be contacted on /forum/smilies/tongue_out_smiley.gif[/img]hillippa@the]phillippa@the kirks.info or 07950 038176 / 020 8852 2351.
Hope this helps.