I'm with the others and I would pursue an
ECV. The
scooter operates with hand power, not leg power. If you stay at a Disney resort there are approved offsite vendors that will deliver to your resort and the scooter will be waiting for you usually by the luggage area. Offsite resorts offer the service, too, but you may have to be present at the time of delivery of the scooter there; you do the same for non-approved offsite vendors. You return it to the same place.
You do have to consider your weight when ordering the right scooter. Weight includes any purses, cameras and so forth. If you are too heavy for a lightweight scooter you will lose battery power fast. Renting a travel, portable scooter is the best; because, you can take it apart and it will fit in most trunks of cars. It comes apart in 4 to 5 pieces usually. There are u-tube videos to show you how this works. You may have a local mobility company and you could visit there and see a demo live with your own car. If you use a car the whole time then all you need to do is bring the battery charger and battery in each night to charge up. If you use your car then you don't have to take it apart until you need to use it. Most Disney resorts expect you to keep your scooter in your resort room when you are not using it if it doesn't stay in the car.
If you need to bring it into the resort room chances are someone will have to hold the door; so, you can get it inside. This will be the same in reverse when you leave the room. The room doors are heavy and it's better to have someone hold the door open. You can even have someone else drive it in and out of the room. Some will move the table and chairs in their room to make it easier with the scooter for getting it in and out. The same holds true with Disney transportation. Someone else can drive the scooter on and off if you don't feel comfortable doing it yourself. I think the hardest for beginners is getting a scooter on and off a bus if you have to use one. Monorails are easier. You wait with the handicap areas to board a monorail.
You will have to get use to the crowds at Disney while using a scooter. There is no doubt in my mind that you will have someone dart out at you and you will need to stop fast. Sometimes it helps if some one is in front of you guarding your turf coming through the crowds. You need to be careful and use all the handicap ramps when necessary; you don't want to jump a curb.
You need to carry your battery charger with you on the scooter in case you need an emergency charge. Usually there is a pouch where you can keep it. There are outlets in the parks where you can juice up if necessary. If you have trouble finding an outlet a Disney CM will be able to guide. You need to watch the battery sensor to make sure you are not losing power.
In addition to practicing at a local store you can go to a local zoo and get more comfortable using one there. Once you get to your resort you can practice at the resort before going to a park.