Hhhhmmmm......strange, I thought you had to be a 'borrower' I.e. named on the mortgage in order to claim the relief, that's how we had to do it when we lived in apt that my husband had bought in his own name.
If they'll. grant it to him and you want to use his first time buyer status now for this, you're not planning on moving, then he will get the first time buyer rate, we have that on our current mortgage, which is in joint names, but because my husband had a property before he doesn't get the first time buyer rate but I do, the relief is calculated separately for each of us and paid to one account