What happens now the Queen has died? Operation Unicorn is triggered after Her Majesty died at Balmoral not London: Royal Train is sent to convey her coffin back to London, Scottish Parliament is suspended and Britain enters 10 days of official mourning

https://www.dailymail.co.uk/news/article-6593747/What-happens-Queen-died-Operation-Unicorn-triggered.html

–As preparations get under way for funeral, the accession process for a new head of state begins immediately

–Prince Charles is now effectively king, although protocol says he will be declared new monarch tomorrow

–William is now heir, followed by eldest son George, daughter Charlotte and youngest son Louis

–Prince Charles will be declared king at a meeting of the Accession Council, usually at St James' Palace

–The Council is made up of all the Privy Counsellors, of whom there are hundreds