Park at N50 53.803 W001 17.597 where you will find some facilities to keep the kids occupied, toilets and occasionally refreshments at the kiosk.
Walk to the clue at N50 53.774 W001 17.613 where you will find a monument with 2 dates.
ABCD-EFGH
The cache co-ordinates are:
N50 53.(A+C)(E+H)(C+E)
W001 17.(H-A)(D+H)(B-D)
Please try and hide the cache as best you can when you put it back.