Carer Allowance , self-employed expenses, form pro81

Hi , I need to fill for form pro81 in relation of my income and expenses as self employed and getting carer allowance.
Is it possible to use flat rate motor expenses instead of calculating all the fuel, HP, tax,MOT ?
Sorry if this have been discussed before ?

Thank you .

It’s definitely allowable on a Tax return: have you tried phoning them to ask?