I think most clinics know (and understand) why we get drugs outside. ARGC referred me to Alis chemist in Shadwell to get HUmira (they gave me the phone number without me asking)
I think it is worth asking your doctor about this rather than relying on what one fertility nurse says.
MOst of us dont get our drugs direct from the clinics pharmacy as its much pricier.
I had Puregon and found the Shadwell chemist already (via my local chemist) and was able to save hundreds of pounds.
Tpo give an example , my first clinic (LFC) charged £300 for 600 IU Puregon. Alis cost me about £235 for £600 IU (and was the cheapest I could find)
I also saved £15 PER VIAL of ORGALUTRAN (£35 at Alis compared to £50 at LFC)
They made no secret of this and the doctor told me I may get the medication cheaper outside the clinic.
BTW Ali does mail order too and so does the chemist in Peterborough, who is also cheap.
Hope this helps
(Incidentally, a private prescription can be 'cashed' in any pharmacy, you are not obliged to use the clinic's own pharmacy supply. Alis chemist told me they have patients going there from all over the place. He is based in E1)