Sorry, answering a bit late now, but it worked for both. It is just water held in place by a gel, and is apparently to promote healing where the wound should stay wet, for which is specifically lists radiation burns, but also worked really well on the outside for a sore arse due to wiping very frequently.
Just an update 11 months after RT in the context of the thread...
Mucus farts gone, probably a few months a ago.
Still consuming less fibre than I used to, to keep stools firm.
Still slightly more mucus than originally when pooing, but that actually makes pooing easier than it was originally - slips out with ease, and rarely any mess when wiping.
Farts - can now tell if they're going to be safe or not beforehand, and let the safe ones out.
Painless rectal bleeding - about once a week, and somewhat counter intuitively, more likely with looser stools.
Going twice as often as I used to, but no problem holding on if not convenient.
If it stayed like this, I wouldn't have any complaints. Will ask onco about bleeding though, as with that, I wouldn't get any useful indication of future bowel cancer.