At week 8 the boot is adjusted, and I was told this would "allow for step through walking" I can not find these phrase on line, so I guess it means walk like normal. But in reality I found this difficult. The boot although excellent is no replacement for you ankle, and so you can still expect some discomfort, as it does not allow the freedom of movement you bodies joints do.
My physiotherapist said I was allowed to go swimming at this point. Although she did say maybe wait until week 9, which I did.
Just as your calf has got weak. . . so has the rest of you. Swimming a couple of lengths of front crawl nearly killed me, although I really didn't care because it was so lovely to be properly out of breath. It is also a good thing to walk up and down in the pool, providing the water is deep enough to cover your nipples. This way you can practice walking without putting your full weight on your foot. I had time to go swimming twice a week. My physiotherapist said "2 or 3 times a week". Don't wear yourself out you are still healing.
Swimming also loosens up you calf muscle in the most glorious way. My leg felt excellent after a swim, and that was enough of a reason to go on its own.
Environmental Consultants London