"My hands and arms are affected as well, writing on the board will be tough and my handwriting has seen better days."

Suzanne
Most teaching nowadays is done on a Smart board, you can use PowerPoint presentations with these and they are hooked up to the Internet so you can show video clips, you can also type with the computer as you are going along(saves the writing). Teaching has changed so much in this new electronic age, my tip would be to try to get another English teachers presentations and amend them to suit yourself( this way you won't be typing the full course as you go along as this would take ages).
There may be training on using this technology that you could prepare over the summer. Good luck