Disability and Accessibility

I've got a wedding to prepare for in a few months, and, let's not gild any lilies, I've gotten pretty fat since I injured my right knee and hip and lost a lot of mobility. I get around with a cane most days, and running/jogging (which I used to do a lot of) is now no longer possible (although I can use an eliptical).

I'm kind of scared to join a gym, because I hear they're pretty predatory with their subscription policies, and I don't know how much use I'd get out of one. I don't know what classes I can attend or what equipment I can safely use, or even what equipment to use for weight loss rather than muscle gain (or can they do both?). Unfortunately, the no-brainer option of "use a swimming pool" isn't available in my area, either.

Does anyone have any recommendations for fitness activities, classes, or equipment that are low-impact on the lower body? Are there exercises I can do at home without equipment that will burn fat? I'm not looking to become an Adonis, I'd just really like to be able to fit into pants smaller than a 46 waist.