Just from my knowledge of genealogy that’s a bit far back. Henry VIII would be about 12 generations back not 25. Also the connection is more direct but through Henry VIII’s sister Margaret who was married to a Stuart. The Electress of Hanover was descended from James Stuart. There are also connections through Diana’s family the Spencers.
Yes, I think you’re much closer to the accurate number than I am. I happened to skim this article...
https://www.express.co.uk/news/royal/1334589/Royal-family-tree-Queen-Elizabeth-II-related-king-Henry-viii-Tudor-times#:~:text=Mr%20Stedall%20wrote%3A%20“Elizabeth%20II,of%20Mary%20Queen%20of%20Scots.&text=”Although%20she%20died%20before%20Queen,direct%20ancestor%20of%20Prince%20William.”
...in Express.co.Uk this morning before reading this on FR. And I made my comment from (faulty) memory. In it, a historian on the British Monarchy says..
“By my calculations, this makes Henry VIII, the Queen’s 14 x great uncle, at which level she has a 1/32,768th part of Queen Margaret’s blood.”