For me it was fear of the unknown along with complete lack of confidence in myself and my ability to cope alone, as well as his almost total control over the finances meaning I'd literally be leaving with nothing.
Now I just cannot wait to get it over with and I am really frustrated that everything is moving so slowly. I want my house yesterday ffs 
We still don't have much to leave with and the longer it is taking the less reasonable he is being about what I can and cannot take, but tbh, at this point sleeping in an empty house on the floor, would be preferable to staying here.
And for anyone who is thinking about leaving but can't afford to, there is support available. We've been getting help from CAB, a local housing project and I am off to see the credit union this morning about an affordable loan for furniture. It can be done, making the definitive decision to leave is scary as hell, but once you've done that it gets a whole lot less scary.
thatsnotreallymyname, you do not have to tell him your plans until you've already left. Go and see your local CAB, there will be organisations local to you that can help. I found that after talking to them my choice to leave became a firm plan that I was determined to see through, rather than me just knowing I needed to leave but being uncertain on how I could leave iyswim?