This could well be a TLDR!
We have 2 power showers and a bath but for >12 months I've been a bath monkey. The reason - a side effect of medication resulted in psoriasis - primarily scalp psoriasis but with angry patches elsewhere - face (esp.), legs, arms, back. Whilst arguing for a change in medication I turned to the results of numerous Google searches and began bathing using, variously, colloidal oatmeal, magnesium 'spa flakes' (probably Epsom salts) and Dead Sea salts. I also used, variously, Aleppo soap, birch tar soap and soaps rich in glycerin, and began using Dr Ratna Tantra's shampoo bar (she of Hampshire Wool Fat fame). If someone had suggested a shampoo bar to me 18 months ago, I would probably have laughed in their face.
I largely stopped eating members of the nightshade family (not easy for anyone raised on potatoes) but have slowly re-introduced them.
My medication has now changed and I
think I've turned a corner, being largely free of the visible effects - but fearing I may just be in remission I've stuck to a lot of my bathing regime. I have some long aged Aleppo soap and also swear by soaps made by Handmade Norfolk Soaps (to which I have no affiliation) and Nesti Dante. I use birch tar soap periodically, although one that I have, though otherwise good, has a hemp oil base, which I'm not a great fan of. I still use a shampoo bar.
If I need to, I use my ever-diminishing Kiehl's Argan Body Lotion (discontinued - I'll never know why) or Boot's coconut oil (not sure if you can still get that either).
Because I'm a fussy chap, my bath is enamelled - I'm not sure I could live with a plastic one - and the towel has to be a good Indian cotton one
Edited to add that I also use the Lush sandstone soap scrub intermittently - a good exfoliant, long-lasting and dirt cheap at a fiver.