MAB,
Gigha Island may be suitable, but I think the runway is a bit better maintained than Lundy.
Ginge, I wouldnt even think about going to Lundy until you have a lot more experience of flying into short rough unmarked strips. also you preferably want a taildragger with fairly large tyres as there are plenty of rocks on the field as well as ruts and holes.
Plenty of better places to try first, like most of the other destinations used for Devon Strut fly-ins, if that is the area you want to go to. If you do go to Lundy then a good time would be at the Devon Strut fly-in , as at least there are people there and someone might have inspected a bit of the runway.