Give your bike a thorough service. Reputable cycle shops will have a mechanic who can do this for you.
Government Fix your Bike Voucher Scheme
As of 28 July 2020, anyone in England who has an unused bike in need of repair can apply for the Government’s ‘Fix your Bike Voucher Scheme’ to receive a voucher worth up to £50 towards the cost of repairing their bike. To find out more, Bike Voucher Scheme.