The limit for claiming over the phone is £10,000. Anything above that you would need to put it in writing
Did you phone the caseworker/team dealing with the security checks or just the regular self assessment helpline?
If the latter, then they'll probably only have limited information they can provide
Norway isn't in the EU, it is in the EEA
I was still in nursery!
I don't think you can do it online as the agent/soon-to-be agent. You'll need to print off the SA400 form and send it through the post I think
As far as I'm aware, both the client and previous agent need to agree to the deed being revoked. I'd try to contact the old agent again as HMRC likely won't budge
Assuming the estimated pay is correct and no personal allowance is given, there could be something else in the code taking it to 1125L such as personal pension relief.
Also as already pointed out, a K code doesn't mean non cumulative, only that deductions exceed allowances. Codes sent in advance of the new tax year will always be cumulative.
Do you have a breakdown of the code?
If it's for 2016/17 then I'd contact HMRC to ask for the year to be reconciled, saves the need for P53 if they hold details of the pension already
Why not just register for SA and file online?