Not 100% sure this is true, but the last set of stamps commissioned before her death, may well be this Transformers set
https://shop.royalmail.com/special-stamp-issues/transformers?gclid=CjwKCAjw1ICZBhAzEiwAFfvFhLZMnanNJ_qf6kohCizftMdZWbWepFAynxtHGTp8WbOa4FHy3kjL1BoCrA4QAvD_BwE&gclsrc=aw.ds
Might have to get the framed one as a mark of respect/they look cool