First up: The Invisible Library is currently available as an ebook for 99 cents from various American sources. (Sorry, UK and other residents. I know how it feels - I'm UK myself, after all.) I think it may only be reduced till the 7th April, so . . .
Nook: https://www.barnesandnoble.com/w/the-invisible-library-genevieve-cogman/1120258722 …
Kobo: https://www.kobo.com/us/en/ebook/the-invisible-library-3 …
In other news, I'm attending the following conventions this year (and possibly others, depending on how things go):
Eastercon - 19-22 April - https://www.ytterbium.org.uk/
Worldcon - 15-19 August - https://dublin2019.com/ (no, not the Colo-Proctology one)
I have seen the UK and US covers for book six of the Invisible Library series, and there is a title, and I hope to share these with you as soon as possible . . .