familysearch.org have the registers of Hanbury from 1574, which they also say are available on findmypast. The actual film on familysearch is only viewable at one of their libraries unfortunately, which I'm guessing are not open yet.
Have you looked through the film on findmypast to see if the years you can't find are missing? (not unheard of).
If your Biddulph family are not in them prior to the ones you've found, perhaps they came to Hanbury from somewhere else? I have families who moved to new places in the 1600s.
I see Humphrey Biddulph's marriage to Grace Clarke in 1682 was some 45 miles (see below) or so away in Yoxall.
Have you searched neighbouring counties to Staffordshire? Took me years to find one of mine who I thought was from Cheshire, and turned out to come from just over the border in Staffordshire! (to be fair, I had to find other pieces of evidence to make sure he was the correct person, as it was a fairly common name).
Added:
There would also seem to be a Humfrey from Yoxall. I have been flipping through searching on familysearch, and not written everything down, but I would be double checking everything. I seem to think I saw a burial for the Humfrey at Yoxall before your Humfrey in 1700 and another marriage?
Also added:Realised there are two Hanburys. The other one is just a few miles from Yoxall. Google threw me a red herring! But I should have checked better.