I found coal tar shampoo to be helpful on the scalp. Can be bought at any chemist

I use tar shampoo. I think nutrogena t-gel is what I use when it’s really bad. I also have a Betamethasone cream (it’s liquid ) that you put on your scalp eczema. Works well for me. If it gets infected I will put some antibiotic cream on it. You have to shower more often but it definitely helps.
I also find that if I don’t shower regularily(trying to shower less) as it keeps your skin from drying out, my scalp gets worse. I can’t win lol

what good for

The body shop shampoo with Ginger has been a lifesaver for me. It's the anti-dandruff shampoo and works perfectly without irritating my sensitive skin. Try using it every other day for a few weeks and then you can use it as many times as you like. I've been using it for about 5 years now and no longer have scalp eczema :)

I use a basic shampoo for the first wah then followed by T-Gel shampoo then a basic conditioner. The 3 steps above work wonders for me.