Some useful links ....
Quekett Microscopical Club: http://www.quekett.org.uk/
Optical microscope primer: http://micro.magnet.fsu.edu/primer/
The Postal Microscopical Society: http://www.postal-microscopical-society.org.uk/
Other societies: http://www.microscopy-uk.org.uk/amateurs/mainpeop.html
Microscopy-UK: http://www.microscopy-uk.org.uk/
OU Intro to Microscopy: http://www.open.edu/openlearn/science-maths-technology/science/biology/introduction-microscopy/content-section-0
Microscopy web site list: http://www.microscopy.com/cgi-bin/MMWWWSites.pl
PTR Optics: http://ptroptics.com
Amateur Photomicrography.net: http://www.photomacrography.net/amateurmicroscopy/index.htm
Kreb's Micro (Photomicrography image libraries): http://www.krebsmicro.com/
Doug Richardson's 'Observations': https://www.quekett.org/wp-content/uploads/2020/02/doug-richardson-observations.pdf
Brian Stevenson's history of microscope and slide making: https://microscopist.net/