He should give you an emergency supply, and he will mark the tablets ,' emergency supply' normally about a weeks supply.
What I generally do is ask him for a supply and tell him that the surgery are walking the repeat script round to him. Most surgeries walk scripts to local pharmacies and ave a pick up service with Boots.
I do it all the time for DD's epipens, inhalers, antihistamines etc. Use to do it for my Seroxat too, back on Prozac now.