Matt has created an Open Street Map showing the Gyms and their Ex raid eligibility.
This is accessible on the following link
https://umap.openstreetmap.fr/en/map/leighton-buzzard-gyms_226213#16/51.9165/-0.6630 . If this needs updating please contact Matt.
Matt also runs the scanners that provide raid and map data on PoGo-map.com. Raids are free but scanning Pokemon, Quests and stops can be purchased for a small monthly fee. For more information see their website.