Nothing like a 50% weight saving, especially if you play safe and take your Lunar exit burn fuel with you.

Looking at the CSM data, fuel for both Lunar orbit entry and exit was only 18 tonnes out of total mass of 24 tonnes. Significantly more than half of that would have been needed to brake the CSM+LM combo into Lunar orbit, rather than only the CSM back to Earth.

Perhaps the best way to look at things is that if such a fuel source existed we would redesign the missions. There would be a sturdier multi-use ground-to-orbit lunar module that didn't split on takeoff - merely refuelled and lifted intact.

The Earth-to-Luna module would not need to carry a LM each time, saving 40% at least of the mission Mass, hence permitting either a smaller booster or a larger CSM. (I reckon it would actually be 50%, since you no longer need the hangar for the LM, either).

Finally, we would probably merge elements of Aldrin cycler orbits and use the free-return figure-8 orbit of Apollo to bring a heavy transfer vehicle there-and-back, with a rendezvous and cargo/passenger module transfer with the Luna shuttle that carried enough Lunar fuel for Lunar orbital injection of the cargo/passenger module, leaving the transfer vehicle to fly back to Earth for free - or minimal manouevring fuel, which would be uploaded at the time of rendezvous.

The cycler would remain in permanent Earth-Moon transfer, visiting Luna every 6 days or so for scheduled or emergency pickups, and being available to carry fresh loads from Earth on a similar basis.

Note that this sort of delivery system implies a readiness to launch a new cargo from Earth every 6 days, or low multiple thereof!