First of all I recommend reading this short e-book that is aimed at young investors.
The book is written for American investors but they same rules apply with different terms (e.g. the equivalent tax-free savings wrappers are called ISAs in the UK).
If you don't anticipate needing the money any time soon then your best bet is likely a stocks and share ISA in an aggressive portfolio of assets. You are probably better off with an even more aggressive asset allocation than the one in the book, e.g. 0-15% bond funds 85-100% equity funds. In the long term, this will generate the most income. For an up-to-date table of brokers I recommend Monevator.
If you are planning to use the money as a deposit on a mortgage then your best bet might be a Help to Buy ISA, you'll have to shop around for the best deals.
If you would rather have something more liquid that you can draw into to cover expenses while at school, you can either go for a more conservative ISA (100% bond funds or even a cash ISA) or try to find a savings account with a comparable interest rate.