Well... this sounds like fun to plan around. While I was aware about degradation of lunar orbits I did not expect it to happen so fast.
Apollo 12-17 were miracles of trajectory planning, basically take a radar reading from earth while the ship orbits over the near side, compare where it SHOULD be to where it IS and adjust the landing computer accordingly
Apollo 15 and 16 had sub satilites, i recommend reading up on them as one of them had super high and low orbits at one point
Apollo 11s Eagle Ascent Stage was left in lunar orbit, due to the Mascons its unknown where it impacted, a group claims it could theoretically still be in lunar orbit but its a small chance of that being the case
The most unrealistic thing about Stephen Baxters Voyage is Moonlab in low lunar orbit, unless they lucked out with one of the few "Frozen Orbits", i.e. orbits where the mascons cancel each other out. i can't remember if they reference it in the book but any visiting crew would have to boost the station routinely, likely from the CSM or possibly the MPLM (Multi Purpose Lunar Module, basically a LM ascent stage converted into a cargo carrier)
That Book Ascent by Jed Mancuso is really good, the best of the "soviet moonwalker who died but was first" genre (Second is Red moon, the one with a proton launched LOK sending a person who doesn't have a choice to his likely doom