I'm fairly sure in my uni the cut of date for leaving your course if 4 weeks, so if you're truly not enjoying it then leave. It can be daunting going against your parents wishes at first, but really, what is a year in the grand scheme of things? Take a gap year and figure it out, just make sure you do something productive that may help to show your parents you're serious about this, and not just mucking around.The worse thing that will happen is that you have to give back some of your loan, and apply again next year.
I would advise you call up student finance and UCAS and ask them what the score is in terms of paying back and applying for uni next year (IF you decide to!), and double checking any cut of dates with them as well as the uni.
Life is too short and too percious to be worrying about what your parents will think. This time next year it will all be forgotten.