I think two different girls like me and I have no idea what to do, help! Sorry in advance for a mass wall of text!

Here's my SitRep:

Fairly sure a couple of girls I go to college (in the UK, so kinda like the last year of high school for those across the pond) like me. I'll call them 'S' and 'C' for now.

I've know S for about a year. We've sat next to each other in Maths since september and have some awesome bater/flirting type stuff going on. Literally every lesson she'll draw something on my arm or find some other excuse to touch me. We spent a day last week revising together at college (we're on study leave) but got nothing done and spent the day goofing around. I couple of friends of mine were sitting with us for a bit and were wondering 'what's the deal with you guys?' and decided to 'leave us alone'. Apart from that we've never really talked that much outside of lessons. We have a few mutual friends but she mostly in a different circle.

I've know of C a little bit longer but we've only really been friends and got to know each other more recently. I first saw her in a class last year and have had a wee crush since. She's now in both my Maths and Chem classes so I see her at least once a day. We've never really had a real deep convo but we chat occasionally. We text fairly regularly, some times I'll text her first, sometimes she'll text me and our text conversations seem really easy to continue. It's harder to quantify but I'm fairly sure she like me. We have almost completely different friends.

So there's a brief breakdown of the situation, I have no idea what to do. We've broken up for exams now and won't be going back except for exams, so I really want to do something before summer starts and what not. Couple of things worth mentioning; I'm meeting C later this week to revise and once exams are over S, myself and some friends are going on a week-long walking expedition, so I can't do anything to make it too awkward between us!

Ta for ya help!