Back in 87, I still has aspirations, so in the September started circuit training. All went well for a couple of weeks, then I broke my ankle playing rough basketball. Moral here - stick to cycling. Anyway, in plaster for 4 weeks, followed by 4 weeks of trying to walk again and a few physio sessions, then a few weeks gentle turbo, followed by a few weeks gentle road rides. Got to the start of the next season in the March, a little behind normal, but not much and the enforced lay off, just makes you more dedicated and disciplined and you soon catch up.
Every break is different, so take advice from the medical people, but fitness will come back.
Good luck Keith