I actually was in shock when I read your post. I cannot believe any receptionist can take it on herself to decide if a condition warrants a GP referral . That is horrendous practice. As others have said, who diagnosed the sciatica in the first place. It shouldn't be as acute as this for 7 weeks, and given the strong medication that makes it even more concerning if it's not touching it.
I would definitely be going to either out of hours or A & E He needs a scan. Alternatively you can opt for the private route , often referral isn't necessary, you can check out your nearest private hospital and they will list their consultants under speciality with a contact number.
Please do not leave this any longer. Back pain not responding to strong analgesia needs investigating ASAP
Is there such a thing as delicious ready meals?