Ouch, sorry to hear about that. It sounded like a legal settlement. But if you prefer girls 30 and up, there are going to be all sorts of opportunities. Japanese girls are far easier to tolerate once their 20s are over; at the same time, however, the ones who are still single at 35 tend to have some sort of fundamental emotional/psychological issues. But if it's just P4P and you're not looking to bring back any trophies, that's not going to be much of a problem. And generally speaking, the older the girls the more open-minded they'll be toward foreigners--not because they particularly favor them but because the average lecherous, pedophile Japanese salaryman prefers girls barely out of puberty and older girls can't be as choosy.
I'm actually at the age where I'm starting to eyeball 40-something housewives. Not sure if that's a good thing or not but it is more economical.
Anyhow, good luck with the language lessons. If you're going to get a prosthetic, particularly one of the types I've seen on combat vets here stateside who've lost legs in war, definitely get it sooner than later so you can get the hang of it. I've seen guys who you can barely even tell were amputated below the knee until they lift their jeans up. And Japan, Tokyo in particular, is a fast moving place. You'll want to be able to move quickly from the second you step off the plane. Getting around Tokyo station on crutches will not be enjoyable. I figure the Japanese government will have to start letting tourists back in by spring if they want any hope of salvaging their Olympics, and by that time our countries (U.S. and U.K.) should have plenty of access to vaccines, particularly with our Moderna and your Oxford/AstraZeneca coming very soon. That's three or four months of practice. Just be sure to practice pull your pants off, as well.