The core of Waldorf education is that the child's education should mirror the inner developmental world of the child. For example, when a child is becoming more grounded in the world, around age 9, you study measurement. When a child is around 13 and starting to spread his wings, you study the age of exploration and discovery. Main lesson blocks are to immerse the child in his own inner reality. History is usually the backbone of main lessons in Waldorf. When we refer to Grade 4 we talk about Norse Mythology. When we refer to grade 5 we are talking about immersion into ancient history. Grade 6 is Rome, Grade 7 is Middle Ages, etc.
That said, Waldorf homeschooling is very, very intense, and very teacher-heavy! I would not really say that Waldorf is a unit-studies method, because again, the point is that you are helping the child discover his world. You don't focus on subjects. You focus on educating the head (academics,) the heart (spiritual development,) and the hands (handwork, using the body, etc.) Everything is based around that. But yes, you use many different ways to explore one topic in depth. If you are studying Old Testament, you are going to be building an ark and making a LOT of little creatures out of beeswax.
You definitely could use the idea of main lesson blocks and immersion into one topic at a time. All of my kids LOVE main lesson time - it is their favorite part of the day.
I do not find that Waldorf Main Lesson Books are anything at all like notebooking. I have done notebooking or lapbooking with my kids from time to time, thinking it would be fun, and found it tedious and disjointed. For our family, MLB's are much more meaningful and rich. Notebooks I would throw away. MLB's we treasure and keep. They are diverse, with writing, copywork, paintings, drawings, poems, charts, maps. Each book is so unique and is something the child can look back on with pride.
I think it is enriching to understand the philosophy behind the educational strategies you use, especially with Waldorf because it is very complex. At the end of the day, everyone has to do what works best for each family and each child. The most important thing is to keep the joy and wonder in their learning.