I actually bought a flowering Miltionopsis Newton Falls two weeks ago at a garden center here (so across the channel from you). It was mislabeled as "Miltonia Newton Falls" though, and they were placed with ferns rather than the other orchids, so not too sure if they stock them regularly or if it was a one-off thing. No sign indicating what nursery it came from either, unfortunately.
I checked their website (
intratuin utrecht) and they do sell pansy orchids though they are misadvertised as miltonia even online and the plant pictured isn't a Newton Falls. They don't deliver these either (the line below the pic says "store only") but you could try calling them and asking what nursery they get them from. There are quite a few nurseries here and shipping is probably not all that expensive given the short distance.
Not sure if it's helpful but at least it's something.