If you are totally happy with it and have that final document there then you can cancel the appeal yes. Just be 100% sure the wording is right with you too though - make sure everything is clearly defined without wooly wording such as "access to x hours" and "consideration to be given to..." etc.
I would wait till LEA send it to school as the 'yep, signed and sealed, now get on with it' document myself. And then doublecheck each and every line for any last minute typos changing 'will' to 'could' etc. But then I'm a cynical old mare
Or you could go for a consent order instead. It should have the appeal heading, and I think it then says something like "Upon the parties having reached terms of agreement, it is ordered that the LA issue an amended statement in the form attached." That then brings the appeal to an end. I like the idea because I've heard LAs talk about withdrawn appeals as if it was some sort of victory for them.