Holly, Firstly welcome, I have a pair of NHS aids, and itchiness is often a problem with me, my doctor will occasionally prescribe a small spray bottle of " OPTIMISE " which after a few days does the trick, but the itch always come back after a time. I have also at odd times smeared the tiniest drop of olive oil on the aid before inserting it, which sometimes helps.
Even if you could afford bought aids, I have researched this with friends who have gone from NHS aids to private bought, and they assure me they are no better, and private aids will certainly do nothing for the itch,