Ok, since the legal age in the UK is 16 and she\'s a couple of months shy, I think that you should go to the cinema with her. You obviously enjoy her company. And consider the outting as a good time spent with a friend. If you really want to persue her, I suggest you to develop some patience if you don\'t already have a storeroom of it. Just be friends with her for now.
Then a really nice to it would be to take her out on a romantic dinner on her birthday or a day near her birthday. Get all dressed up and make a reservation. Then tell her that you\'d like to start a relationship with her.