Have you looked on rightmove.com for any suitable flats to rent to see if there is anything in your budget on your own?
Also you could make use of the week whilst he is away by doing a budget for your single life and viewing accomodation. If you could afford somewhere where you want to live, you are halfway out of this situation.
Then you can give notice to your landlord, and do not tell your dh where you are going straight away, just say you are going to stay at parents/friends house.
Once you are securely in your new property you can let him know if you wish, but it stops him causing disruption during this process. By the time he knows you are serious about it being over you will be in a new home.
Of course this only works if you can afford somewhere, but if it were me I would be very willing to compromise on space/location to be free quickly.
Also whilst he is gone can you get together all important documents from birth certificates, insurances, financial paperwork, your and dcs pasports and give them to someone you trust. Make sure you have separate bank accounts, transfer your share of joint savings to your own bank account, and make sure he has no access to anything of yours, change passwords etc.
If you think he will kick off when you tel him you are giving notice to the landlord, could the dcs stay with grandparents for the night to avoid witnessing any unpleasant behavior? And could a friend be close by?
I know it must be daunting, but please use the week to plan your escape and keep focussed on your brighter future.
fingers crossed for you and your lovely dcs.