Travelling to Ireland with naturalisation certificate

[hinano]

Apologies if this topic has already been covered but I couldn't find anything doing a search. I had my citizenship ceremony yesterday and I did JCAP. I need to travel to the Republic of Ireland next Friday (15 June) and I don't think my British passport will have arrived by then. I know that the UK and ROI have a Common Travel Area so there's reduced requirements for documentation travelling between the two countries for British and Irish citizens.

If my British passport does not arrive in time, can I just use my US passport with my British naturalisation certificate at Irish immigration? I am flying into Dublin. US citizens have visa free access to Ireland anyways, so I assume it wouldn't be a problem to enter Ireland on my US passport if they don't want to let me in based on the naturalisation certificate? My primary concern is coming back into the UK, but I have never had my documents checked coming back into the UK from ROI. Any advice that anyone has would be appreciated! Thanks.

[cyclina1]

You cannot reenter to the UK as citizen in this case. If you use US passport to enter the UK, then you enter the UK as visitor. The custom will require you to show evidence that you will leave the UK, or you will be blocked. The cert is not a travel document. To use the US passport enter the UK legally, you need a right of abode in your US passport, which need months to apply for. And you are applying UK passport so you even not allowed to apply.