Can my employers do this?

[HarryFindlay]

My employers want me to work in a different location to the one on my contract, I will be using my own car, am I entitled to any fuel expenses to cover the extra mileage?

Many thanks

[buildersmate]

Yes - in line with the company's policy, which is hopefully 40p per mile - the maximum that HMRC permits without it being a taxable perk.
But be aware that your employer may try to limit your claim to the marginal difference between your current home to work distance and your new workplace to home distance. This is called 'triangulation' by HMRC.