I don't where your local bike club is. I know the club I belong to in Bath, recognised the problem with the Sunday "social ride" still being 50-60 miles at a pace some people struggle with. As a result we also run rides on Saturday that are shorter and slower (25 or 40 miles at 10-13mph or so). They are usually groups of about 6 or and people are happy to bumble along with the slowest.
There are two other bike clubs in Bath (that I know about). One also runs slower shorter sessions to bring people on and the other one is the generally more sedate (that's not a dig, they just like to admire the views) CTC.
Don't just rely on the website, e-mail the club and ask. I am sure you will get a friendly reply and good advice.