Hi OP, first of all I want to say I'm so sorry you're in this situation, and that you are absolutely doing the right thing by stepping away and looking after yourself. Financial abuse is serious (and for your comments it seems other domestic abuse is also happening...).
Now, just going to brainstorm a bit:
Do you have access to your joint account? I.e. your own bank card? If you are named as an account holder then you should be able to move money in and out of the account even without a bank card. The first thing I would do, like others have suggested, is open a private, sole account. Talk to your employer and arrange for your future pay to be paid into your new account. Then, when you are already to leave, I would transfer your previous earnings that have been going into the joint account on to your sole account and leave the joint account - BUT I would go to the bank first though, and request any statements and documentation you may need from the joint account, as once you leave the joint account you won't be entitled to anything documentation wise. Even if all you want is a statement from when you were in an account holder they won't be able to give it to you anymore.
You said you were worried you'd lose your income as you may not be able to continue working once you move. How often do you get paid? Every 4 weeks? Or every week? For example, I get paid every 4 week, paycheck comes in on the Friday for the work I did up until the previous Saturday (eg, I get paid on the 17th of Sept for the work I did/will do until the 12th). You should have a good look at the calendar and make sure you time you leaving just as your paycheck to goes into your sole account (I only say this as you wouldn't want your partner to find out you are leaving right? You want to be gone without him knowing you are planning it right?)
I would also figure out how you can maximise your earnings just before you leave so that the first payment that falls into your sole account can keep you going - can you pick up extra shifts? If you really don't think you can keep working once you move I would also talk to your employer and explain you will be moving away and unable to go into work from X date. Make sure you don't leave without notice as then your employer can without paying you your last week of work, or more depending on how much notice you need (and fail) to give. Perhaps you can also use up annual leave to give you an extra couple of weeks' income even after you've moved away. This should hopefully cover your in-between period of time, and after that you should be ready to receive Universal Credit, or similar.
Lastly, I have read previously on posts on escaping abuse the following advice: buy gift cards at the supermarket with your regular weekly shopping - your partner won't be able to tell from a bank statement that you bought them as it will only say "Sainsbury's", for example, and you can then use these to buy food and supplies in the future. Lots of places you wouldn't typically think of can be very useful, like you can even buy groceries through amazon so getting an amazon gift card would help you cover food costs once you're gone. Others that come to mind are Argos, Boots, M&S. Alternatively you can also divert some money by requesting cashback at the till.