I'd run it standard and see if the miss goes away. Then drive it like that until the coilpacks have been done. A new set of standard specification plugs won't cost the earth. Depends how old the current ones are. I have seen miss-fires on a tuned MK4 GTI from worn out plugs.
Coilpacks are quite a lot more robust on the MK5, compared to the similar ones from the 1.8T. I have not read of that many failures TBH.