[TokuKnight89]

Been thinking about signing up for Brit-Box, but there are concerns about what is truly available via that option.

For example, Hartnell's last regular arc, "The Tenth Planet", seems to be missing in its entirety!

Is that merely an example of still-missing arcs, or have some arcs that have been rereleased to DVD/Blu-ray in the past few years (with possible animation to cover the gaps) still not received a digital upload up to this point?

It should be noted that "The Tenth Planet" is not alone in this. There are other arcs which are clearly not available on Brit-Box. That one was just a convenient and noteworthy example.