Wait, that's MY toilet, my suspicions are confirmed!
Actually, it's rather a nice 'little room' Simple and clean design.
I've never installed one of
these, (although others here will have) but I think you could fit it to a panel that went over the front of the cistern, if there's enough space without it interfering with seat up or sitting position.
Does the noisy flush annoy you when in there, or does it disturb rest of the household at night etc.
How high is the ceiling anyway?