One problem may be that you are using the word "help" to describe the BF's potential involvement in housekeeping. It's not a matter of him "helping" you with "your work", it's a matter of him understanding that half of the housework belongs to him by right.
Determine which places in the house are shared; let him have a place in which to be a slob. Don't touch that place. Also, if you have two bathrooms -- one for each of you -- then YOU must have the bathroom that guests also use. You will keep that one clean, and he will bathe in squalor. When he gets disgusted enough, he will clean it. (Women always screw up on this one. "Why do you clean his bathroom and then get mad about it?" "Because it's the one that the guests use." Trade!)
Follow through on all threats. In other words, if you say you are going to pitch anything left around, pitch it.
I have three brothers, and I was the household maid. I have no sympathy for women who wuss out in this area, and then complain. We must be tough! I did not clean my brothers' rooms. I did do the laundry, and the rule was, what is in the hamper gets washed; what's on the floor gets ignored. Personal stuff left in the common area (i.e., living room) gets THROWN into the personal bedroom, regardless of how it might fall or what it might hit.
For the common space, make some ground rules and stick to them, but -- and this is very important -- make sure you give him his own space in which to be as foul as he likes.
"This is totally unfair! Just because I'm from another planet, I don't have rights? I mean, doesn't the Geneva convention protect extraterrestrials?" (Stargate)