You can take some antihistamines but they have to be prescribed by a GP - a pharmacist is unlikely to sell them to you OTC. And the GP can prescribe you emollients as well to help with the itching. I had terrible pregnancy itching in my first pregnancy - totally sympathise. But it will go away, promise
Sympathy OP, I'm just about keeping this under control at the moment with Piriton and steroid cream from the GP . Look up PUPPPS / PEP for a little more info, I've found oat baths and Aveeno skin products helpful but coal tar soap from Amazon seems popular too. Do talk to your MW and get a blood test done, as this can sometimes be a symptom of obstetric cholestasis X
A friend who's in a medical field and very into alternatuve remedies says it's my lymph glands trying to clear toxins and I should use Epsom salts in the bath but not to suppress it by taking steroids, anti histamines etc. I would dearly dearly love one day of feeling like a normal human again. I expect that day to come in about twenty years - what have I got myself into?!