Hello teabagwoman. I wanted to post some helpful thins I have found out about doing hydrotherapy, and my apologies if you and others already know this.
It may be possible at your local pool, depending on facilities. But beware of 'ordinary' Aqua exercise which I doubt would suit you - though you can ask to go and view the class and talk to the instructor.
Some public pools put aside time for folk who want to walk & exercise, and have 'lifts' to get you in. My local pool used to do that, but it was still a bit cool for us arthritics, and they have suspended this facility since Covid.
It is often a good idea to contact a physio as they often know local facilities, and will of course, advise you on exercises:
www.csp.org.uk/public-patient/find-physiotherapist/physio2u
True hydrotherapy pools are expensive to build and maintain - they usually have flat access and are maintained at about 34 degC. They are sometimes found attached to specialist schools and hospices. Some of these will allow occasional, vetted access in return for a donation. They are wonderful - I have been lucky enough to use 2 in my time!
Exercise pools can often be found in gyms and hotels. The one I use is at a gym that costs me £36 a month. It has a constant flat floor, at about my chest height (I am 163cms) which is about right. It is kept at about 31 degC (a normal pool is about 28/29) and it is accessed by wide, shallow steps that have railings.
It is easy to use without getting the head and neck wet, so folk do keep glasses & hearing aids on.
Be aware that some of these, in an attempt to drum up custom, will describe themselves as 'hydrotherapy' pools - although I don't think the term is protected, I think you do have to ask exactly what is provided, and ask to view the pool.
Also ask what changing facilities there are, and what are the best times to use the pool. Mine has protected times for private exercise, but a friend uses one (in a prestigious gym) that is very busy and has no protected times.
Mine is also a small pool (about 15x10 metres) so not really the kind of pool a 'real' swimmer would want to use. so it is mostly used for exercise, or for gentle swimming. Anyone who wants a proper swim would use a 'proper pool', so that keeps it a little quieter.
Good luck!