Hi, yes you should have your file covered plus you supply charge extra for wear and tear for the use of your car.
How you work that out, l’m not quite sure if the numbers. But as a nanny who used my own, this was the agreement we came to.
I did a quick online search and came up with this
“ The basic rule is simple: An employee can be reimbursed for his business mileage in his own car at a rate of 40p per mile for the first 10,000 business miles in the tax year and 25p for each mile thereafter.“