AQ, itching at night definitely eczema related, ime. Also ime, gp's tend to be a bit rubbish at finding creams that work. They start with the cheapest and work their way up but I never found the prescribed stuff to be very effective. I can tell you what works to some degree for ds2 though.
Bath in plain water but cover them from head to toe in emollient before they get in the bath, then afterwards, pat dry v gently and cover again with thick layer of emollient. All the bath additives inflamed ds2's eczema, plain water is much better.
Hairwash right at the end, just before they get out and rinse whole child with shower head/cup of clean water to get rid of shampoo residue. I only use Simple Baby shampoo because it's unscented.
Bath once or twice a week maximum.
Moisturise dry bits at least twice day. Use steroid creams while it's red and inflamed, if you apply it really thinly it won't be harmful. Best emollient I've found is Pure Potions. It's not on the NHS and it's relatively expensive but it does last a long time (3-4 months). There's something chemically in all the GP creams that ds2 reacts to, the PP is just olive oil, hemp oil and a few other bits.
Grobags are good but keep them in the lowest tog possible and with the fewest layers under as possible. Ds2 always itches more when he's hot in bed.
We found switching to liquid rather than washing powder (Ecover, but he's also ok with Daz) made a bit of difference. Definitely use non bio though.
That's what helps ds2. I've stepped up the moisturising over the last couple of days and his skin's much better again. I don't think there's anything that will completely get rid of it but all those things certainly ease it.
Jabber, how did your mephew's wife get on today? Any news?