In reply to petegunn:
Not used either of the above campsites before. I can however recommend the Bosherston campsite (it's £3 a night, has portaloos), if you want to make pretensions towards civilisation the St Petrox site is good in dry weather (becomes a mud bath if wet, I doubt my local mountaineering club will stay there again after a particularly wet weekend last year), another good option is the campsite in Lamphey.
For north pembroke my uni club uses Glan-y-mor campsite which is pretty pleasant.
A 50m rope will get you into most areas without any issues.