Given its proximity to transport, I'm putting this up as the new front-runner option...
http://www.nationaltrust.org.uk/main...?basecamp=7020
It looks very central and affordable with train stations and buses near by. It says limited availability, so if that falls through, this is my second choice...
https://sites.google.com/site/thorpefarmbunkhouses/home
It allows for camping outside if we need the extra space of my super massive tent of insanity. It also makes it easy to work out costs for each person (£12 each per night).
Third runner is...
http://www.holiday-rentals.co.uk/p93165
And back up...
http://www.peakpub.co.uk/camping/
I'm going to make some enquiries this week (assuming I don't fall ill again
) and see what each will offer. By the end of the month I'd like to have a place booked.