RedFlyer – My FFP have always and only ever been used to redeem flights for business travel. My company paid for my business flights, so they are entitled to the benefits, not me.
Miles earned from my credit card company for personal expenditure are deemed by HMRC to be a discount, and therefore not taxable. These I have used for personal travel, which in all cases has been to bring my family to see me when I have been working abroad for long periods.
I have also always carbon offset my flights at my own personal cost.
European employment law is weighted heavily in favour of the employee, quite rightly. Not sure what the unions add to the equation these days except job insecurity for it’s striking members. (How ironic!)