@ Rochey – You don’t need to spend vast sums but a little outlay will stand you in good sted. If you pick your night/spot then you could be alright with nothing more than a sleeping bag. A bivvy bag will give you lots more scope though, as will a sleeping mat of some sort. If you just want to give it a try then I’d pick up a cheap foam mat (easily under a tenner) and something like a Hunka bivvy bag from Alpkit (£30). If you really don’t like it you’d sell the bag for £20 pretty easily. As for a sleeping bag, if you wear your clothes and pick a sheltered spot then just about any bag will stop you dieing at this time of year.
@ Santacoops – I’ve taken one of mine. She stays with you all night, you don’t really know she’s there. I wouldn’t dream of taking the other one, he’s fine in a tent but I think a night in the great outdoors would blow his mind!