Do whatever you can to put yourself into a position where you can earn good money.
Whether that means a new job so that you're not working night shifts, undertaking training to get a qualification, or doing a demanding job/traineeship or take on a time consuming role for a couple of years to break into a new industry while someone is there to help with childcare, with a view to taking it easier in a few years time.
Set yourself up a "running away fund" which can cover deposit, several months of rent and some furniture etc so that you can physically leave.
You say "partner", not husband? If you are not married then make sure you have a separate bank account now. Whatever you save is yours and won't need to be split.
Check that there are no keyloggers or spyware app on phones, tablets and laptops. Change passwords etc. once you start planning however much you try to hide it your behaviour changes and these guys tend to notice it. Make sure you lock down all your devices so that he doesn't have access to them.
Any valuable documents should be copied and be stored away from home so that he can't hide them from you. Passports and birth certificates - originals. Any financial details for joint assets, copies. If you have joint savings in his name try to get access to your half.
If you have sentimental items, again store them away from home so that they don't get damaged/destroyed if he gets vindictive.