Lost media is a crapshoot. That’s basically like asking for the missing Dr who episodes or that movie about the clown that leads the kids into gas chambers at Auschwitz that Jerry Lewis did. Unless you’re really lucky at some yard sale you’re basically waiting for some industry producer to die and their tech nerd grandchildren to clean out their house and leak cool shit, or someone to finally catalog archives of remote broadcasting stations, or whatever.

Even then it’s still a crapshoot. Missing Dr who episode? Everyone wants those so when they’re found they get the fancy restoration treatment (assuming the person who find it realizes what they have, of course). But controversial shit like the holocaust clown and the sitcom you referenced? There are people who are probably happy to see that stay buried. See: the holocaust clown movie is not actually lost but the people who have copies refuse to archive or it in any meaningful way or exhibit it because they feel it’s tasteless or whatever. Censorship wins, though tbf the movie was described as just kind of shitty by people who saw it.

As for the show you want there is at least one episode leaked online which I assume you’re aware of because it’s all over the place, youtube, internet archive, etc. in addition this guy on youtube claims to have the whole series and appears to prove it by posting the VT clocks, which are preepisode slates used by channel 4. This could be easily faked though. In the comments he describes not wanting to release it in hopes of pursuing a legal means of release in 2017 (his video is posted 2016) which pushes towards fake because that timeline is obscenely short for doing all the licensing nonsense involved in properly releasing a dead show. He’s a corpo bootlicker (straight up says in comments won’t release out of respect for the rights holders, because apparently having your hard work never see the light of day is more respectful than acquiescing to social (likely advertiser) pressure and shelving it).

As far as I can tell that’s the only lead but if his video isn’t faked it suggests the tapes still exist. If this is the case your other avenue would be tape trading, which is this whole other crazy thing. This is really hard to get into because you kind of need to have a source for stuff that is rare and be willing to hoard it, which is shitty. There are people who hoard specifically to deal only with other people who hoard, which is so fucking dumb and it’s like who cares, but they do it. This is a whole thing and it’s hard to get connected with but the easiest inroad is a place like myspleen or forums dedicated to preservation (like the forums about restoring the original Star Wars trilogy, 4k77 and harmy and such). Every once in a while you’ll see people dump a bunch of 35mm scans onto myspleen or rare screeners, shows like this in much higher quality than ever seen, etc. sometimes it’s just a dude being sick and sharing but sometimes it’s one of those tape hoarders realizing that this one has been passed around so much it’s basically worthless and burning it for upload credit (which is functionally worthless on myspleen but w/e). And sometimes it’s someone taking a moral stand or whatever like a year ago or so someone posted like 20 35mm scans that were circulated in those groups but not to torrent normies. But if someone has this show it’s probably one of these nerds and they probably want some rare weird shit in exchange for it, like you have to buy a $2500 35mm print of Halloween 4 and send it to some rando who will clean and scan it professionally