Do I go back to a sleep bag?

[Lavender14]

I recently switched ds (coming 3) out of a sleeping bag and into blankets and duvet and toddler pillow. However he moves a lot and keeps kicking them off. It was fine in summer with the warm weather but now the weather's turned he's been waking up cold repeatedly in the night. Anyone any decent recs for a 2.5 tog sleep bag for a 4 year old (he's really tall) or am I doing something wrong here with the bedding situation? He can also throw a leg over the side of the cot he's in now but isn't able to pull himself up and over yet. He's only done it a couple of times and seems to recognise that if he tried to actually get out he'd fall so I'm not too worried just yet though id say we're definitely not far off taking the sides down. But I'm a bit wary of putting him in a sleeping bag incase he takes a notion and attempts it without full use of his legs if that makes sense?

I'd put him in a cot bed or single bed and have a single duvet that you fold half under the mattress to keep it in place all along one side. That will probably be enough, but if not we did cotton pyjamas with fleece pyjamas and socks on top if it was really cold.

I think out of the cot and definitely not back into a sleeping bag. Cotbed or single bed with single duvet like PP

DS was in a low bed from about 14 mo. Never got out of it at night until very recently (he's now 8) and would shout for us if needed. He didn't seem to be able to keep covers on for quite some time either, but recently has generally got the hang of it. They figure out pulling them on eventually

These are great https://lovetodream.co.uk/products/sleep-suit-long-sleeve-quilted-cotton-2-5-tog-green-moonlight