I started itching early on and switched to mum to be type toiletries (shower gel, cream, bubble bath). Could be psychological but haven't been itchy since, so I'm not changing back! Various brands available, I've mainly used Champneys, and if you join the Boots parenting club they're included in the 10-points-per-£ offer - sometimes with 3for2 or similar too.
I was horribly itchy from about 13 weeks for a few weeks - doc said just hormones/one of those things (there is a more serious cause of itchiness to do with liver function but not usual until later on) - she recommended just a plain aqueous cream, you can buy at boots etc, don't need prescription. Smells a bit, but it did help (may not on scalp though, sorry!), although I can tell you it did go away eventually for me, hope it does for you too. You have my sympathies, it drove me mad for a bit, was covered in red scratches, DH almost bought me some mittens like they put on new borns!
Oh yes my neck and chest got so itchy! I had to wear a scarf all evening when we went out for dinner once as I have scratched myself so much it looked like I had severe sunburn . Get yourself to boots and slather it on