Have you considered competitive trail or endurance riding? It may be easier on your body than jumping, and a winding sandy trail up and down through woodlands, with an occasional water crossing, always seemed much more fun than anything done in an arena... just sayin'. As for horses; after four decades I can say with confidence that for intelligence, good sense, willingness, responsiveness, comfortable gait and breathtaking beauty, all in the same package, the answer is; Arabian.

Breed has nothing to do with a horses ability to jump / suit your needs.

I would find a solid lesson program and try out the horses they have available to you. Sounds like while you are building your fitness level a school horse type would be perfect - something that isn't hot, doesnt take too much leg, and will be forgiving and can teach you - as opposed to you trying to teach it.

I have a friend with CP who rides and volunteers at a local theraputic riding program we have close by. Its great for him because helping out and walking along side students gets him exersice, and he is able to ride most of the horses who need a little refresher once a week after the more mundane "pony ride" types they give the rest of the week. Plus, he doesnt have to pay as much to ride since he volunteers some time too. Might be worth looking into - he does a lot of stregth training with weights as well but this has really helped him maintain a fitness level he can be comfortable with.

I second Mel'sAuntie. Consider competitive trail and an Arabian/Arabian cross. Very athletic and sensible horses with hearts as big as all outdoors. We do have a bias, but it's based on our history.

Yup. What she said.

Great idea to get back into the saddle.
Prior to putting your foot securely into the stirrup I would start getting in shape before you ride. You will be doing your equine companion (of any breed) a disservice if you are not in moderate fitness.
Before mounting your riding comeback get into a moderate state of fitness. For example start walking to get leg muscles Stronger and to develop some cardiovascular fitness.
Riding is an excellent way to develop those fine core muscles required. And leg muscles and arm muscles... Heck all muscles but let's not forget the horse does have to carry us and we should be able to soy correctly.

Arabians are great - we used to have one - but perhaps a gaited horse would suit your needs better? My housemate has CP, and trot is what gave him the most trouble when I let him ride mine, even though he's got a very soft trot.