My suggestion would be 29" frame and build it up
TA fork – there's only the Reba Team or Manitou. Reba's are very scarce on the ground, so choice there looks academic.
You could go for a HT Banshee Paradox – very fun bike and takes 2.4 in the rear so plenty of cush. Not sure what the biggest size is. I know you asked for suspension but the 29" wheel in the Paradox gives alot. The other choices would be Swift of Niner (although I'm not personally a Niner fan)
An excellent choice would be a custom steel HT 8)
Specialized decided not to offer 29er's in the UK following last years sales figures. I picked an FSR Stumpjumper frame (5") from the US (1K GBP). That's going over your budget though, but maybe you could stretch it