Thanks for your reply 'Yomper'
I wouldn't say we are entirely unfit, just haven't done too much exercise over the last few years what with work etc.
I have started swimming 2 weeks ago and go every week day in the hope of getting a bit fitter and I walk places when the sun is out. The other two are going backpacking in New Zealand at the end of May/Early June for 3 weeks so hoping that will help them two!
We also have planned a few one day practise walks between 5-10miles (such as round trip captain cooks monument - roseberry topping - 7miles) which should be good...infact we are hoping to do one either this or next weekend.
With us we will be taking a 4 man tent, "bedding", clothes (waterproofs etc), and some light food for the first day (lunch). We haven't quite worked out what we will do for evening meals - we have discussed taking a stove or disposable BBQs? - unsure though is this reasonable?
I do have all the equipement (well, hiking boots, those things that stop water getting into boots, waterproofs, large rucksack etc).
It started as a laugh at first, but with the charity thing added on it makes it a bit more of a challenge, and I am really looking forward to it!