I'd head for Dumfries & Galloway. We went to the area for the first time in May last year and loved it. We stayed at Mossyard. The lower field is right next to the beach and sea - it's beautiful. There's also toilets on this field as well and they're kept very clean too. The washblock however, it at the top of the site. There are plenty of EHU points in this field as well.
------------- 2024:
February: Broadstone Park, Coleford
March: Bucklegrove, Rodney Stoke
Easter: Llandrindod Wells, Powys
May: Carmarthenshire
July: Dorset Volksfest + Wilksworth
August: Gloucestershire Vintage & Country Extravaganza
August BH: TBC
September: Undecided
October: Bull Bay, Anglesey
Don't forget to leave a review of the campsites you have visited this year or last!
Mossyard is pretty, indeed. Plenty of reviews too. I’ve never managed to stay there, as it does seem to book up.
Might be for another trip however as it’s beyond the OP’s driving time limit.
Another vote for Drumroamin Farm although it's around 125 miles from Keswick so at the upper end of your time requirement.
I also enjoyed staying at Solway View/Balmangan Farm, this is around 100 miles from Keswick. Nice walks from the site down along the coast and round to Brighouse Bay.
Don't forget to leave a review of the campsites you have visited this year or last!