Have to echo jimjams on the wet wrapping thing. Like you, we found we were up 4-5 times a night re-applying cream (sometimes, we thought unnecessarily, but you can't ignore a child who claims to be itchy!!).
We were referred to our local eczema clinic, and had a great session with the eczema nurse, who showed us how to apply the wet wraps. We were actually given a new type of wrap - by Tubiform - which are a series of garments, rather than the old style bandages that you have to cut to measure. This has, apparently, cut down on the time taken to apply them.
Our dd was given a book called 'Kimberley wears wet wraps' (which did sound a bit like an awful porn title to dh and me!!). It explained to her why we were doing it, and what she had to do to help.
We've been doing the wet wrapping all summer (mainly because of the heat), and have noticed a real difference. Dd's skin is better than it has been for ages, so much so that we were able to treat her to some ordinary pyjamas for a few days last week (until the hot weather returned - boo!).
The Tubiform stuff is expensive if you can't get it on prescription (about £35 a set of full body wear, and you need one wet set and one dry, plus one or two spare sets to cope with accidents). However, we've been told that they are now available on prescription as of 1st Sept.
I think you are well within your rights to ask nursery to reapply cream. Our dd needs more every 2-3 hours, especially after sand or water play. We wrote down the procedure for them, and supplied a pump dispenser to make it easier for them. We also supplied some soap free 'soap'.
Some times I think it's just nervousness on the part of the staff - they think it's 'catching' or very time consuming. Perhaps if you offer to demonstrate what's needed, then they'll come round. Good luck though.
By the way, can anyone recommend a sun cream suitable for eczema? We've been trying Proderm, but it doesn't seem to irritate any less than anything else.