I swear by this argan oil shampoo: https://www.amazon.co.uk/dp/B004YRTZG0/ref=cm_sw_r_cp_apap_4AksE83VXAVs3
I also use this super moisturising hair food; no build-up at all it's like 98% natural/biodegradable: https://www.amazon.co.uk/dp/B07L5WGS2X/ref=cm_sw_r_cp_apap_6OJoOBhDOjpHB
Used to have dandruff and also a super itchy scalp, now no dandruff AT ALL and occasionally an itchy scalp if I don't take the time to moisturise properly. I wash my hair once a week but feel free to tailor it to your hair!