Any legalities here must be considered personally, as must every individual's morality and upbringing and beliefs and principles, etc., etc., etc., and because of these things and also because of too many contradictory "laws", I shall not focus on them. I don't think I should give you any legal advice; seek a person who you can speak with in-person for that, who you can trust.
Don't get carried away! Remember - it is possible to have sex and it not mean anything loving. If you are just horny, then find a nice, respectable, clean person of your own Race. Please try to discern between getting your rocks off and falling in love and being infatuated. It can be so complicated and heart-breaking. If you're sure you can sleep with someone and it be just about the horny sex pleasure, then OK; if not, then tread very carefully; if you don't know, then again - tread very carefully. If it is 'puppy love' or you are in love, then good luck! If you are experimenting, then again - please tread very carefully! If they are a Spiritual Satanist or someone who is open to such things, and you are performing Sex Magick, then good luck! Be responsible.