Fleecy airbed cover, 3 seasons bag, fleecy liner inside the bag, thermals and probably a thin fleece over the thermals too. Thats all year round for me really (although I have been known to ditch the fleece once or twice).
Yes I know I am a wuss but never underestimate how cold it gets in this country on a night. I have known days in summer when it has been red hot during the day but during the night its been really chilly. And remember that you are basically sleeping outdoors - a tent will give you a certain amount of protection from the cold but not much.
we all have 3 season bags and I normally feel the cold even in Aug but this Easter we wee all too hot!! so didnt need the extra fleece liners or fleece blankets that I'd also packed!
------------- Taffy
2012 Planned
Easter - Cornwall
July scout camp
August North Wales
I've got a three season bag (apparently) but I was freezing last week in West Sussex. And so was the overnight temperature, given the frost in the mornings! This was with fleecy blankets over and under us, and extra quilted throws too. To be fair I was the only cold one, but I spent most of the night making sure my 3yr old didn't wriggle out of her covers.
I was thinking about getting a Gelert Beyond pod, there are some on eBay. And some thermal undies. And some Sealskinz socks. And possibly a balaclava.