Have you applied to the home office for confirmation of your Permanent Residence yet?
Forget about "indefinite leave to remain", it does not apply to EEA national. "Permanent residence" is what applies to EEA nationals.
A registration certificate is proof of your right to work in the UK. It is not Permanent Residence. Permanent Residence is your right to remain permanently in the UK without working, which essentially means being free of immigration time restrictions.
If you applied for naturalisation before 12/11/2015 then you would not have needed to apply for Confirmation of Permanent Residence. However, the rules changed after this date and so any applicant for naturalisation applying after 12/11/2015 must have obtained a confirmation of their Permanent residence.
If you apply without this then the application for naturalisation will be rejected and you will lose the very expensive naturalisation fee.
Please remember to leave feedback.Tom
You're welcome, but please remember to leave feedback..Tom