Have Tax Questions? Ask a Tax Expert for Answers ASAP
You have stated that you are a non taxpayer. If you think you are entitled to a repayment , you should complete Form R40 - Claim for repayment of tax deducted from savings and investments.You can download the form from HMRC website here https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/419506/R40_M__internet_v2.0.pdf
More information on this can be found here
https://www.gov.uk/government/publications/income-tax-claim-for-repayment-of-tax-deducted-from-savings-and-investments-r40
I hope this is helpful and answers your question.
If you have any other questions, please ask me before you rate my service – I’ll be happy to respond.