Using Images Without Thumbnails

I have a page with an image on it. Currently, when I click on the image, it acts as a thumbnail and launches a larger picture. Instead of this, I would like it to link to a different page. However, I cannot find out how to prevent the full size image loading.

If you look at the page
https://www.craftedcopper.co.uk/wordpress/parts/ruby-panels/

I want users to be able to click the small parts diagram and launch the same page as that linked by the text below the image, rather than just getting a larger version of the thumbnail.

I am not sure whether it makes a difference, but the image and the adjacent price list are in a table one row by two columns, for ease of placement.

Any ideas, please?

Thank you.

James.