There was a great site called discomusic.com and they had a forum where someone was posting all the Record Mirror Dance Charts from September 1975.
Unfortunately the forum was closed late last year and the website is now a shadow of it's former self.
Fortunately someone else has created a new website to post these charts and the legendary James Hamilton columns. They are currently up to June 1977 and are posting regularly.
Here: - https://jameshamiltonsdiscopage.com/