I actually didn't know Roald Dahl had a day. A few weeks ago I found out that September 13th is Roald Dahl day and I knew we could have a lot of fun with that in our homeschool.
Diary of a First Child has a great list of things to do, eat, and watch. Her list includes a link to the entire BFG movie on youtube, which I didn't even know existed. We watched BFG On Monday. On Tuesday we ate peach cups for snack while watching James and the Giant peach on Netflix. We also checked out Charlie and the Chocolate Factory (that's the newer one) and Matilda from the library. We are planning to watch Chocolate factory as a family and have a candy extravaganza. I picked up some peanut butter M&M's and Sour Patch Kids for the occasion. Unfortunately, Willy Wonka candy is not gluten free.
We also read The Enormous Crocodile and are reading Matilda because it is mister's favorite. We haven't read either before and they have been so much fun. The Enormous Crocodile is a quick read and is very silly. It is a great Roald Dahl book if you are reading with younger kids with shorter attention spans.