Is 15 to young to finger my girlfriend..?

I'm 15, and in the UK (so I'm not American, like most people here :P). Me and my girlfriend have been together for about 5 months. We both turn 16 in November, until then, we're not going to have full sex. However, we've discussed it, and we both feel ready for things that are close. Like fingering and hand jobs. We usually hang out at a big-ish park after school confined by trees. Do you think she'd be comfortable being fingered there? There are only like, 10 people there within about half a square mile of dense trees. Thanks for your sensible opinions guys. 10 points best answer!! ;)