Ah thanks so much for the detailed advice!
I think my main concern is keeping it in. I struggle to lie on my side without immediately triggering a toilet trip so perhaps ill chill on my back as long as possible and see how i fare.
Also is there a definitive amount of time it needs to be in there before its fully absorbed? Is half an hour the benchmark to shoot for?
No worries. Well...to begin with you might struggle keeping it in anyway, so it's good to do it on a protective mat or something ... some suggest doing it in the bathroom to begin with so you're close to the toilet. It's good to fight the urge as long as you can, enemas can make you feel like you need the toilet when you don't, and if you ignore it the urge can go away after a few minutes. Don't want to have an accident though if you can avoid it. But on top of that, if you're flaring and going to the toilet a lot or with a lot of wind, you might feel very uncomfortable and genuinely might need to go. Again do you best holding it in but there's gonna be no way to stop an urgent stool obviously. Just see how long you can manage, a few minutes is good to begin with if you can do that, you can build it up from there.
As for lying down, a lot of people say 20 minutes is fine and some do shorter than that. I like to take slightly more time doing everything, just so it's as relaxed and comfortable as possible. Sometimes if I feel very uncomfortable lying on my side, rolling over onto my back helps, but I believe the enema has to have been in at least a little while or it'll just come out. I think the earliest I've personally rolled over is 10 minutes, I try to do 30 so I'm sure it has the best chance of staying in. Movement will probably not help you keep it in, but experiment with it, I've found sometimes the only thing that's relieved the uncomfortable feeling is walking around, but then I don't think that's going to be an enema that's going to stay in very long.
And if you expel it quickly, you can always do another one, after a clear out you may be able to keep it in a lot longer / all night.
Of course, when you're not flaring these things are much easier, but we often need to use these things when we're least likely to find it comfortable and retain it! Good luck with it though.