Was 40 myself last April and me and my husband and two other couples (another 40th b/day girl as well

) splashed out/stayed in a Tipi last year.
They can not be booked until the same time as the tickets got to be paid, so I doubt they will be sold out by the time the resale happens.
It is just one big space, but it was ample for us 6, we had narrow campbeds and still room for the big rucksacks and about 1.5m square in the middle. However some of the Tipis are a bit smaller depending on how many of you stay in there.
We loved it there, beautiful view, the solar showers not to busy mid afternoon, lovely camp fire lit in middle of field

with chance to meet lovely neighbours. Would love to stay again this year, but can't really afford it - at least we were lucky enough to get tickets
I hope this helps
Roll on June!