It'll be fine The (very very small) hint of saltiness will just make it taste that little bit more 'grown up'. I make all my short crust with salted butter for just that reason (except maybe with a lemon meringue pie, for example, where the whole point is insane sweetness).
Just wanted to pop back and say my fruit tart was a success so thanks everyone for their advise! I had to improvise a bit and my pastry is a bit more like a shortbread biscuit but it tastes delicious! yay