I really sympathise with you tillysmummy. Our dd (2.5) has had a dreadful time with her eczema since about May. The hot weather over the summer was terrible - I never thought I would be so glad to see the cold weather return!
She was waking 6-7 times a night, and in the end we were prescribed a mild sedative for 2 weeks, plus a course of wet wraps. We used these solidly for 8 weeks from mid July, and they certainly helped, although it was a real palava and felt as though the improvements were slow. DD was very patient (we called them her 'special' pyjamas).
As you're a member of the Eczema Society, you probably have advice coming out of your ears. I would echo the bit about overheating - I'm amazed at how much more comfortable dd is in a really cool room, and we resisted for ages putting the duvet back on her bed. Other things that help her are not getting overtired (having a nap during the day), or stressed (hunger does it for her), and being really careful about what we wash her clothes in. The central heating hasn't been an issue for us so far, but we have kept it low, and on only twice a day. Not sure what we'll do in the depths of winter.
Unfortunately, even though her skin has been heaps better over the last few weeks, we have been left with a habit of her waking at least twice a night, and needing one of us to go in and reassure her. She used to be a 12 hours straight through the night baby, so this is really galling (I guess I should be grateful that she ever slept like this, but I'm 6 months pregnant with no. 2 and sleep deprived!!).
DD seems to have forgotten how to settle herself. The difficulty is that she is now in a bed, and potty trained during the day, so uses needing a wee as an excuse to get up in the night, and sanctions are difficult. As she also has a kidney condition, we can't get tough with her over this - it's best for her to empty her bladder if she needs to. So I think we're stuck with it until she's big enough to get herself up in the night.
At least twice is better than 6 or 7 times.
Sorry not to be able to offer more advice.