Good news Gabe!
I think swimming would be an excellent start back into things. Post-op you just want to remember that the tissue remodeling (ie healing) is not finished for 6 or so months, so you want to gradually build up the stress on the surgically repaired tissue. I would probably start indirectly with ab work when you are ready. In other words, instead of planks or something like that, I would focus more on other compound movements which will activate the core, but not overly stress it until the tissue is better prepared.
Hope that helps ...
