Not entirely sure what you mean by letter of acceptance. However you only become a British citizen once you have attended the citizenship ceremony and have received your citizenship certificate. Letter of Acceptance -- it's what everyone has on their 'Timeline' entries, they list things like 'biome...

May I ask a follow-up question, for clarity? The BRP needs to be returned within 5 days of attendance of the citizenship ceremony or receipt of a certificate of citizenship. I am assuming that these are NOT the same things as the letter of acceptance. I have international travel plans scheduled for ...