WFH & mileage since 2006 - tax relief?

Billy74

Hello all - basically I've worked from home since 2006, for a 3 companies. Never had a 'WFH' allowance in my package.
In all that time I've been driving a personal car on business (not commuting) on 45p pm expenses, probably 9,000m pa. 
Trying to find out if & what I could claim in tax relief. Roughly 50/50 split WFH/driving.

For mileage I think it's the 2.67p VAT of the 16p petrol element of the 45p? - but receipts needed?

Also think there's a flat rate £4 per week for WFH - but can't see how or where to claim this?

I have no fuel receipts, but I do have records of expenses/mileage claimed.

Any advice hugely appreciated!

Dazed_and_C0nfused

Do you mean you were using your own vehicle on business and were reimbursed 45p/mile by your employer?

Did you ever exceed 10,000 miles in a tax year?

WFH claims that aren't because of WFH due to Covid-19 are much trickier to justify.  Why do you think you meet the eligibility criteria?

And you cannot claim anything for tax year 2016:17 or earlier now.