Hello, I'm Keith and happy to help you with your question.
Gov UK is quite positive in its advice on their web site;
Their advice is:
'If you have to travel for your work you may be able to get tax relief on the cost or money you’ve spent on food or overnight expenses, called ‘subsistence’. You can’t claim for travelling to where you work, unless it’s a temporary place of work. Expenses you can claim tax relief on from your business journey include:
Public transport costs hotel accommodation if you have to stay overnight
Food and drink
Congestion charges and tolls
Parking fees business phone calls,
Fax and photocopying costs'
Frankly I am quite astonished at the advice you have received from an HMRC official assuming that the expense is wholly and necessarily incurred.
I have deliberately not mentioned the use of your car. The easiest way to claim these is using the mileage rate method. This reimburses you for all vehicle costs including capital costs. It is 45p per mile up to 10000 miles per annum and 25p thereafter.
I do hope I have set your mind at rest on this matter.