Fourteenth Birthday Weekend <3

Hello, I am going to be having a fourteenth ‘birthday weekend’ next week and I thought I would consult this website for ideas. On the Friday night three girls, one boy and I are going to be watching Harry Potter in the cinema and then heading back to my house for a sleepover. The following day we are going to the beach with around thirty other people, which should be fun, and on the Sunday I am going to a concert type thing with a few of my friends.
Any ideas on how I could make this weekend that little bit more exciting?
Any ideas for the sleepover, or the beach? There are boys and girls at both, so I don’t want to be boring and do girly stuff :’) also remember I am under a budget. Thank you! :)