I'm in total agreement with
@himtoo
You've been prescribed the medication presumably because you met the criteria for needing it.
Preventing you from filling in your prescription for weeks means you won't be getting the treatment you have been assessed as needing.
I would be ringing the surgery and saying 'I realise you need a med review/fasting test before I get my repeat prescription, but I need the meds asap. Can we please bring the appt forward, or can you issue me with a short term interim prescription for the next 5 weeks.'