So your CH is fine at 120 since 120-150 ppm is what we recommend to help prevent foaming. Your TA of 110 ppm is high for a spa and is part of the reason why your pH is at 8, but you can get your spa ready to go and even use it while still adjusting the TA over time -- to some degree it will self adjust when you keep adding acid to maintain the pH.
So I would add the recommended amount of Broma-Start to the spa which is usually 1/2 ounce per 100 gallons so for your 1000 gallons that would be 5 ounces. Then put bromine tabs into your floating feeder and if it has a dosing dial set it nearly fully open since you have a large spa. Finally, add an oxidizer to activate some of the bromide to bromine right away. You can use chlorine bleach as that oxidizer or if you have some non-chlorine shock (MPS) or if you have Dichlor you can use those if you want. Just note that with bromine, you might need to shock with chlorine once every week or two to keep the water clear. If you use chlorine as your oxidizer after each soak, then maybe you won't need to shock much if at all.
As for how much chlorine to add, you should try and start each soak with around 2.2-4.5 ppm Bromine so you add whatever it takes after each soak to accomplish that. I'll give you some rules of thumb for this based on your bather load. You can use
PoolMath to calculate dosages, but it's set up for FC (i.e. chlorine) so you'll need to divide your Bromine Now and Target numbers by 2.25 and enter that in as FC. So to go from 0 to 4 ppm Bromine, that's 2 ppm FC which in your 1000 gallon spa would need 3 fluid ounces of 8.25% bleach.
As for how much oxidizer to add after each soak, the rough rule-of-thumb with no ozonator and a hot (104ºF) spa is that every person-hour requires 3-1/2 teaspoons of Dichlor or 3-1/2 fluid ounces of 8.25% bleach or 7 teaspoons of non-chlorine shock (43% MPS) to oxidize bather waste. The real rule is to add whatever you need to so that you still have roughly 2-4 ppm Bromine for the start of your next soak. Note that the bromine tab feeder should be adjusted so that it maintains a background bromine level in between soaks -- you do not use it to try and oxidize your bather waste after each soak unless you plan on being VERY consistent with your usage.
As for your TA and pH, if your pH is high, use acid to lower it. The acid will also lower the TA over time. That's fine and let it drop, but if it gets to 60 ppm or so and your pH is still rising then tell us and there are some other things you can do about that (lowering the TA more and using 50 ppm Borates).
Bromine tends to be easier than chlorine because of the slow dissolving bromine tabs that maintain the spa between soaks. If you soak every day or two, then chlorine is no big deal, but if you don't soak often then with chlorine you need to dose in between soaks. The main problem with bromine is that it smells different and some people don't like that. It's also a weaker oxidizer so may have some trouble keeping the water clear for as long. Finally, the disinfection by-products are technically worse with bromine than with chlorine, but the levels are low overall so most people ignore that.