General methods to integrate and practice natural building in a traditional stick home

When we bought our property we planed yo tear down the ran down house one the property and build a small home. Short version we were convinced to remodel the old house which made since yo create less waste. We have most the bones exposed and a new roof.
With our remodel we want to use a lot of natural materials and try to learn/practice some natural building techniques in our remodel. We have plenty of clay but may need to bring in sand. Where should start to get our hands dirt. Can I do some crazy cob inside or maybe just stick to light straw clay slip?

In my (inexperienced) opinion, I think light straw will be the way to go; putting strawbale onto the existing structure will mean that you lose square footage (as the bales are wider than the framing) and, unless you already accounted for it, your new roof overhangs will probably not be long enough to shield your cob as well as you would like(not to mention the existing foundation might not be beefy enough to handle the weight of cob.)

As far as interior walls, maybe look at wattle & daub? thinner, lighter, and fun for the whole family

You can always save cob for outbuildings though, then you'd get the whole experience building something to 100% all by yourself!