Expenses - Does it matter how the customer pays?

My casual p/t job is paid per contract. Contract payments include an allowance for necessary public transport costs (which I will eventually claim as an allowable expense). Where a job requires additional costs e.g. fuel, I have to claim that separately from the customer and is payed on top of the initial contract payment. From a self assessment perspective does it matter? My current thinking is just treat all of it as total turnover and then claim all the transport and fuel purchases as allowable expenses.

Hi
That is correct.