I'm thinking of dropping out of my plans to live with my current flatmates next year before anything is properly organised
What is wrong with your roommates? Why don't you want to live with them anymore?
Well, sometimes my flatmates try to impose house rules I cannot accept.
It's okay to have second thoughts before making a major life change, but if you already agreed to move in with your flatmates, it would be rude for you to suddenly drop out. Try talking to them about how you feel instead.
I can't have people telling me what to do.
Be sure to give your roommates time ahead to prepare. You could also try to negotiate with them to lessen some of their house rules. If they don't budge, then let them know you are moving out.