Yes, the Economy package has everything you need for history, so then you would just add the science package to cover history and science.
There are other items you may want to consider buying too. The devotional, Little Pillows, and the Hymns for a Kid's Heart--I've heard those are great (ours in on the book shelf...we start Bigger in just a few weeks!!!
Also, the Deluxe package has books for storytime, though you can use any books you choose. Storytime meets reading skill standards, like analysis of character, plot, setting, mood, genre, etc.
Lastly, you'll need to make sure your language arts and math are covered. HOD uses Singapore for math; Rod and Staff for Grammar; Emerging readers or Drawn into the Heart of Reading for reading; and for handwriting, either Cheerful cursive or Italic D (or you I think you can choose to do copywork if your child is not ready for cursive...not sure about that). Or, you can use anything you want for LA and Math--it is easy to supplement.
(The Basic package will include your devo, music, math, and grammar).
Hope that helps...sorry so late in responding! Welcome to HOD and feel free to reply if you have more questions.