Taking a look at random small parish councils, it seems that information such as minutes is normally published as a PDF that contains reusable text. I found one that published as HTML which also allows reuse. Scanning is appropriate for, say, the annual return which is normally hand written and signed. Although publishing as an image may not be unlawful, it certainly isn't best practice, and you could point out that it is not the way most parish councils are doing it. If small parish councils can do it, then town councils certainly should be able to!