Sustenance expenses as an itinerant worker

Hi, have seen conflicting information regarding claiming tax relief on food and drink as a PAYE employee. I work as a mobile engineer travelling from my home address to client sites around the country. I am paid door to door (home) so my work starts as soon as I start travelling until I reach home again. The sites I work at are different each day with no more than a week at each location (usually just one or two days). I travel home again each evening and rarely stay away. I believe that this means I am classed as an itinerant worker? I often have to buy food and drink from service stations/supermarkets etc. Would I able to claim tax relief on these purchases? I already fill in a tax return for pension contributions tax relief as a PAYE employee and have read that I may be able to also claim for expenses on travel expenses?

Hi Dylan Butler
The cost of food and drink consumed, and accommodation used, by a trader is not in general an expense incurred wholly and exclusively for the purposes of the trade, since everyone must eat in order to live.
Such costs are (either wholly or partly) normal costs of living incurred by all and not for the purposes of trading.
Please see BIM37900 onwards.:
BIM37900 - Wholly and exclusively: expenditure having an intrinsic duality of purpose: contents
Thank you.