>>2785385I'd say 0C is more like a 3 season, would probably do for this time of year as long as you're not sleeping on a mountain. Can't give you too much advice really, I bought a cheap 3 season viking trek bag off Amazon a couple of years ago for £30. Still going strong and have comfortably been down to 3-4C no problem. Do your own research though, I'm sure there's much better stuff out there depending on your budget.
Not sure about tents, been looking for one myself. The Vango 1/2 man ones seem to be pretty decent. A lot of people like the naturehike cloud up, my brother has one and it gives you a lot of space but I don't think they're great in wind.
As a beginner /out/ist in the UK, you can't go far wrong with the D of E recommended kit, tends to be cheap and decent. I don't trust it myself cause there's so much Vango stuff on the list that it makes me think there's some dodgy dealings going on.