so i rang my FS to ask if there was a blood test to see where i was in the cycle and the nurse said there was and to ask the GP to give me one or book in to see the FS (which i want to avoid)

two of the GPs i go to refuse to give me a blood test. One saying theres no such a thing.

How do i get a GP to give me one and do you think the medical centre GPs are more lenient?