Grow some balls and tell your parents that your life is your own, and you are going to do what you want to do with it!!!
I am not trying to be derogatory; I am trying to get you to see that if you don't stand up for yourself and have the courage to fulfill your own goals, you will regret it for the rest of your life, no exaggeration.
If you don't convince the admissions staff tomorrow, take another gap year: do not spend £30k on something that you don't want. Use that year to get work experience. This will benefit your application for next year and will allow you to get stuck into the field of work that you 'actually enjoy!'