If you go to gov.uk living in Spain , click on the link to prescriptions, and it will show you a scale of charges.
as a state pensioner, my diabetic husband pays 10 % of medications plus his expensive diabetic tablets have a further subsidy.I don't know if you will get that as a worker. It is capped according to income, as a pensioner, but not, I believe, workers.
i think you will have to pay 40% of your prescriptions
the practice nurse gives him needles, test strips and the testing machine, but the finger prickers we order from Advanced care products in UK , as it is cheaper.
if you buy the strips from the chemist they are very expensive.