Hi, this is Jim, thank you for the question - I will resolve this for you.
Sorry to hear of the issue. The school should not be charging you for a service which they cannot offer. The essential term to the contract you have with them is that you pay them - and in return they provide the tuition.
If one of these essential terms is not able to be carried out, in this case due to an external event being the pandemic, you can demand a refund even if their terms say "non refundable". This is because a contact can be terminated if "frustration" occurs, meaning performance of the contractual terms is impossible - due to the pandemic for example.
If the pandemic is not the reason why you want to cancel, then the contract will be scrutinised if you took them to court over this. If the non-refund terms only apply to enrolment fees then fine - the court would say the non-refund does not then apply to the tuition fees. As an ambiguous contract is generally resolved in favour of a consumer, being yourself.
If the school disputes this, threaten them with a report to Trading Standards (tel: 0808(###) ###-####. You can use the attached letter to try and get your money back - if you had to use the UK courts, you need either a UK residential address in order to receive court documents, or you need to use a UK law firm to act for you.
I hope this helps and answers the question - please feel free to ask me anything else.
Have a good day,