Dr. Drib, thank you for the suggestions. I bought the Delphi Classics Edition. The advantage of this is that it has lots of material about the diary, the disadvantages are that it is edited (with rude words cut out, even the mention of his wife's periods, "after the absence of her terms for seven weeks").
The other main disadvantage is the way the annotations are laid out. I haven't put this on my Kobo yet, but in Calibre the annotations appear as small font within the text, rather than as numbers leading to footnotes.
The most useful version I've found so far is a website. The diary begins here:
https://www.pepysdiary.com/diary/1660/01/
I downloaded (to Calibre) and took a look at the version from standardebooks. I prefer the way the annotations are laid out in this, with numbers leading to footnotes, but, like the Delphi version, it is edited for "rude" words. This one also suffers from a lack of index. When it's on my Kobo, this might appear in the "burger" icon.
I suppose what I would really like, in an ideal world, is an ebook version of the Latham and Matthew edition with all the rudeness which Pepys intended. No way am I spending so much on physical books (which I now consider a liability because of the space they occupy.)
I'll probably combine the Delphi Classic with the standardebooks and online versions.
Thanks for responding.