How old are you? How well off are your parents? If you're likely to be under 25 at the start of medicine (if you get a place), and making the assumption that your parents have money on the basis of the fact that they can support you through one degree, you might get nothing by way of DH bursay (it's means tested, and a few of my GEP friends have had nothing but their fees paid and the non-income assesed part of the student loan -> basically about £3.5K a year to live on, so GEP is not always the golden hello it's touted to be).
All this is a long way off, but I seriously would talk to your parents anout the idea of taking out your student loan and putting it away in an ISA - offer to make one of them a counter signaturey if it helps. If you don't get in to medical school you can pay it back and make a small profit, and if you do, you'll have some money to help you.