Get a small oil radiator. It doesn’t use a lot of electricity, and amazing to keep the room warm. We have one in every room, as our heating turns off for the night.
We use a long sleeve vest, pyjamas, socks and a 3.5 tog sleep bag with sleeves and she’s just fine in this.
You can buy togged sleep bags with arms, so you could do a long sleeve vest, onesie and one of those.
@Jessica- Daisy Ann I do the exact same!
Long sleeve vest, sleep suit, cardi and 2.5 tog sleeping bag with a blanket on top. But you can do 3.5 tog sleeping bag or sleeved bags.
Put a little jumper over her baby grow maybe or a top between her vest and babygrow to give that extra layer. You could even add some mitts if she will allow. We have a 3.5 tog sleeping bag I picked up from Asda and use it for colder nights.