Looking from 17/08 for 4 nights for a family holiday of 6. Within a 2hr drive from Wirral would be ideal.

You might possibly find something by using site search and other filters like static caravans, late availability on ukcampsite.co.uk - very short notice though. Good luck!

I would highly recommend Machynlleth Wales.
It is a lovely little town that I have been to many times and is situated in Snowdonia National Park.
The site Greenwood posted is a very good resource.

try facebook marketplace as well

Me too, one of my fav places.