Briar Patch doesn't do boarding
There is one over at Takeley, it's a franchise of the Bunnery, contact details here:
http://www.thebunnery.co.uk/asp/index.asp
£10 a day for four isn't bad, that's only £2.50 a night each.
The Tiptree Hopper group lady also does boarding to raise money for the RWA, maybe you could try her?