You do still need to fill in the finance forms, because if you don't get into Cambridge and accept your insurance you will want your loan.
If fill in the PN1 after results day, you have a good chance of not getting paid the money until October or November time.
You may as well start organising your gap year now, because you don't want to end up doing nothing for a year!
I suppose asking Sheffield to defer would probably be the easiest option, but if you don't want to wait the year then I don't see why having two different years of entry would be a problem.
If you want to defer - who would you ask, I am planning to take a gap year but I am uncertain of who to email, I did not state defered entry on my UCAS appplication. Would it be the admissions office most likely?
You apply as if you are going to your firm, therefore you say you have deffered entry.
They ask you to send some form you get when your offer is unconditional from UCAS, and this will be proof of whichever uni you are going to.
If you end up going to the insurance, I think everything will go smoothly. Many people will be in the same situation, and the loan companies will surely have procedures to follow for such situations