If your grand daughter wants to go to a Russell group uni , which, given her GCSE results, should be her aim and her school should be really encouraging it, then she will need to research her options thoroughly. Warwick for example requires students who do not have A2 Chemistry to do a supplementary course. I know for example that King's College London used to give their 1st year Engineers a maths test at the start of the degree and if students did not get 90% they were required to do maths on Wednesdays until 9pm. I think (as someone who has been working in the secondary sector for 20 years) that your granddaughter has great potential and should be aiming for a prestigious institution and should tailor her future courses to getting into one as a degree from a Russell group uni will carry more weight than say, a degree from an ex-polytechnic.