Reporting additional income

I get payed through PAYE but I need to declare additional income, for example from the bank accounts interests which falls into the taxable amount, and also want to declare Gift Aid amount which changes every year. I know that for the professional expenses I need to use p87, but is there a specific form for the above income or do I just write a letter to HMRC? Many thanks for your advice. Kind regards

Hi, While your bank interest will be automatically declared to us by your banks and building societies, you can confirm these amounts, and declare the gift aid you wish to claim, by contacting us in writing, by phone or webchat, via:
Income Tax: general enquiries
Thank you.