CR001 wrote: The certificate would have been sent to your local council, unless you specifically mentioned another council in the relevant part of the form.
As mentioned by
CR001, the council that you must take your oath at is your local council, unless you specifically nominated another council in the form for naturalisation that you submitted.
If you have got the approval letter, I would suggest calling the council and checking whether they have got your certificate and if so, booking the ceremony.
Expect a long delay. The earliest date at the council that I had nominated was two months after I got approval, but that was fine by me.
I am not a lawyer or immigration advisor. My statements/comments do not constitute legal advice. E&OE. Please do not PM me for advice.