Considering how noobish I am with the Doctor Who novels, I almost understood that.
I believe it was given as an example of how canon can work and still be changed to still work with the older versions of the canon. Something Star Trek sort of does from time to time (See Star Trek: Enterprise).
The mentions of the Federation and money to me have always suggested that the Federation (or at the very least Earth's) economy changed sometime after the Five Year Mission, or had changed prior to it, but the creep of the credit lingered for several years before fading into the dark corners of the Federation. By the movie era it was more or less gone, and by the 24th century it was a thing long gone, as some officers that didn't get out on the fringes of society often had little concept of money or even barter.
As for the topic of military, because we are given the concept that Starfleet is not a military as a fact, more than once across several centuries, we the audience are meant to accept that as a fact. There is the provision that during extreme crisis that Starfleet might be basically drafted into being the military for the Federation, which would stand to reason during the prolonged periods of the conflict with the Klingons and probably the Dominion War, but outside of those times, Starfleet is not a military by its own definition.
It would make some sense of the times when Kirk was a soldier and then he wasn't a soldier. The before time being before the Organian Peace Treaty was enacted. After that time Starfleet got itself undrafted and returned to its non-military self. Until the Organians left and the Maroon uniforms came with the Klingons becoming aggressive again. This could also be why Admiral Kirk retired the first time, due to Starfleet being drafted again. But changed his mind later, but seemed perpetually depressed. The loss of his son by a Klingon blade didn't help matters at all. This lasts until after Praxis explodes and the hostiles end due to the Klingons not being able to afford it. Starfleet gets undrafted again after over a decade (with some harsh supporters of the notion that Starfleet should crush the Klingons to make sure they never try something against the Federation again), and eventually get back to their old Deep Space Exploration business.
The Excelsiors get refit for exploration more extensive exploration duties, the Constellations, underpowered as they are, start long term explorer missions. The Ambassador-class gets constructed to better handle longer than five year missions. The Cardassians show up, and a low key war begins, but it never seems like it or the other wars are really all that major, being very local affairs. Starfleet does not get drafted again, but sometimes enables defense missions near the Cardassian border.
The Klingons recover after 50 years and start to make waves, but before things heat up again, the Romulans start attacking Klingon outposts. USS Enterpise is lost defending one such outpost and secures the Klingons as allies of the Federation due to their honorable sacrifice and courage in battle (worthy of a Klingon I suppose)....that it was an Enterprise, a ships with a long history with the Klingons, makes it even better for the Federation. The peace holds and decades more pass with Starfleet being Starfleet.
Only the Borg appearing shakes Starfleet to promote defensive and tactical improvements in the face of a terrifying threat. The Dominion comes and the Federation eventually settles that war may be the only way they can remain free, and the peace is slowly choking the Federation and its usually methods of diplomacy, science, and engineering are failing to counter the Dominion....All they had left was war or serving the Dominion. Starfleet choice war as their only hope.