I'm new to wild camping but I did a couple of days in the lakes trekking and sleeping last week and I discovered two things. 1 my pack is far to big and heavy (70L) and the vango trek self inflating mat gave me back ache for days which is unusual as im an otherwise healthy 27! It also doesn't pack very small.

Some of the gear I carry include a zephyros 2 tent, a down sleeping bag and a wee stove and the usual survival bits and I would like advice on what size of rucksack to take? (Suggestions welcomed). Budget £60 max- ish. I have been looking at 45 and 35 litre packs such as Lowe alpine cloud peak 45 and the terra nova laser 35.

Secondly I need a mat that will be kind to my back and offer the best possible nights sleep. Happy to spend here as its my health were talking about. Climbing helvellyn with an aching lower back was not as enjoyable as I hoped the trip would be.
Thanks in advance.