As you will be using your own car for business travel, it will depreciate in value partly because of business mileage. You can claim tax relief for that using the AMAP rates. That claim will also cover all the running costs of the car including fuel, insurance, MOT, servicing, road fund licence but not road tolls or are parking fees.
You will almost certainly be covered by Example 2 here
. At the end of the tax year, you should be issued with a P11D which will show the total value of the fuel purchase costs charged to your fuel card. See the last paragraph under "Income Tax position". The P11D should give you credit for the private mileage deduction from your salary.
If you complete an annual self-assessment tax return, then you would enter the P11D figures into your tax return employment pages using the corresponding box numbers from the P11D and then claim tax relief using the AMAP rates in the expenses claim section.
If you don't complete an annual self-assessment tax return, you cam make a claim for tax relief for your business mileage on a P87
Take a look at EIM31205
for more information.
I hope this helps but let me know if you have any further questions.