@CallMeSyd Well, know that you're being prayed for, buddy. Hopefully the surgery won't be shoved off for too long; I've known (of, I didn't know him personally) a guy who had a collapsed disc in his back, had to have a surgery for that. He lost quite a bit of his range of motion afterward, but the surgery was successful, and he went back to his job. That was a good 10 years ago, may be more. Every situation is different, but I've got a fair amount of confidence that the trade-off will be worth it, in your case.
Was in the garage getting an alignment on Hazey the other day and caught a commercial on the TV for a compression band called "Beactive+" that's supposed to help with such spasms and sciatic nerve pain. The people in the commercial didn't have the nerve damage that you have, so it's not just a simple fix for the real problem, but the sharp stabbing pain between the leg and back were described as what it prevents. May be have a chat with your doc about something of that sort, of course along with the physical therapy (don't slack on the workouts, it's a daily grind, but can actually do a lot of good).
Also, talk to your doc about seeing a chiropractor. Since you've already got nerve damage, one false move could be devastating, but after a poor judgment call I made during a construction project, a year or two of chiropractic care really fixed me up. Some things, you need medical care for, but for other things, you have potential alternatives.