Hi John,
Undecided about duration, however we could offer either indoor accommodation (in the form of floor and camp bed) or use a local campsite. We have no dates decided yet, but are fairly flexible, would need to be a weekend to fit in with various working patterns of the adults.
Though looking at you location I am wondering if a day in the summer when we are down in Cornwall (near Cawsand) for a week maybe better for you.