Rules and regulations about pubs is a bit peculiar. I used to run one. Things may have changed since I was a publican, but it used to be like this:
Although magistrates can impose conditions upon the licensee, a pub is essentially a private house. As such, the owner of the pub (who is not necessarily the licensee), is reasonably free to discriminate against whoever they wish. This can be seen by the number of pubs/clubs that bar under-25s, for instance.
I believe that as a result of this, there would be no easy way to compel a pub to allow disabled access.