Haven't had time to read all the responses, but I was previously in a situation except H in and out of work for 7 years... In receipt of JSA in between, seemed to be a total charmer in the job centre explaining how he was full time carer for a child (erm bull) and couldn't travel too far / do certain jobs / work certain hours etc etc. No job quite right! Also everything going into a joint account.
Definitely get an account for yourself, with your wages paid into it. Pay all DDs from there. For me, I continued to pay him an amount every week for a while, which was what he was expected to live on.
Once you've decided to separate you are no longer obliged to pay him a penny. If you are separated, even if still living under the same roof, he is entitled to claim JSA as a single man. Then it is means tested without your income being taken into account, and he will be entitled to benefits. Need to be able to demonstrate properly separated i.e. keep finances separate, no longer pay him cash, don't sleep in the same bed, don't socialise / eat together or do chores for him.
It was hard - some of our bills were in his name and he refused to change the name on the account meaning I couldn't change DDs. So i cancelled the DDs from the joint account, and he started being chased for payment. Told him I'd pay it once it was in my own name.
Getting him to leave the house was a saga in itself. For my own self-respect I gave him a lot of time to get himself sorted, get over the shock (even though he was an abusive @rse). But ultimately he's a grown up and needs to take responsibility for himself not sponge off you.
Changing the locks not really an option unless he's been physically violent.