Students coming to the UK are eligible for "Transfer of Residence Relief" as explained in (UK) Customs Notice 5
In particular parts 6 and 6.1. This explains that if you use an import agent to ship your effects there is a 'procedure code'.
If you carry the goods yourself you make a Declaration by entering either the Red (goods to declare) or Green (nothing to declare).
Part 6 "To be eligible for ToR relief, you must come to the UK to attend a school, college or university for a period of full-time study of at least 12 months. You must include details of your course and a copy of your offer letter from the education provider with your application.
You may bring belongings for you to wear, furnish your room or use for the purpose of your studies."