Thanks for the great response.
In answer to a few responses. Yep I've definitely considered burning or throwing the tent away a few times. However it's new and a decent one so thought I'd try everything before going too exteme with these little visitors.
The ticks from the image sent are the ones at the Larva stage. So small I had to get my phone camera and zoom it in to confirm it was actually a tick. The problem is, they are so small you can't see them on the fabric of the tent at all. I've been getting a small wet wipe and wiping the tent to confirm if there are others, as they are easier to see against the white wipe. Every wipe is covered in them.
I've starved them for a few more days now. They're now in the freezer to hit them while they're feeling low. Then tomorrow, the tent will be carefully put up and sprayed with a tick killing spray (containing permethrin) I got from a pet store. I'll spray several times then use the wipes to see I've got any movement left. I've also heard leaving it out in the sun can be good for me, bad for them.
I'll keep you updated. Hopefully this thread could help an equally unfortunate tick covered camper.