You cannot claim the mileage allowance if you do not own a vehicle that's being driven for work.
For this Year you can claim
If self-employed and using your own vehicle, you can claim Mileage Allowance at a flat rate instead of claiming against income from wages/salary. If you're an employee, claim the mileage tax relief instead.
If you purchased the vehicle particularly for work, you may choose to claim capital allowances instead.
For your specific business needs
At a time that suits you