Re: swimming ?
Have you considered swimming lessons? Swimming is a great exercise for cardio and general fitness, but I can understand your worrying if you aren't a particularly capable swimmer.
The pool where I used to work offered adults swimming lessons, where lots of grown-ups would come to learn. Perhaps your local pool does?
If not, then just keep trying - you will get better in time, and no one "deserves" to use the pool space any more than anyone else, so don't feel bad because you can't swim well.
Also you can get a float to take with you and hold onto so that you can just work your legs sometimes. If you have vision problems then you can actually get swimming goggles that have special lenses to correct vision impairment (it's like wearing your glasses at the same time). Don't know how much they cost though, or how easily available they are, but I've known people that had them.