To move as much water as reasonable, I got three plastic, 90L outdoor garbage bins with lid from my favourite DIY shop, Wickes. Priced at £8 each. I also used several builders buckets for gravel and decorations. Builders buckets are available at under £1 from any DIY shop or similar.
For the fish, I used a big, round trow-type bucket, about 20" (50cm) across and about a foot deep (30cm), filled with about 8" of water, a few plants and a couple of bog-wood pieces in there for good measure. I bought this one at Wilkinsons for about £5, but I later found some that actually looked better at Wickes for similar price. I also purchased, several weeks ago a Rena Filstar 3 filter that I moved to the tub as I started to catch the fish.
I started by filling my rubbish bins with water from the tank. Using two gravel-cleaners in parallel made this quite quick. I didn't fill all the way to the top for two reasons: 90L of water weighs quite a lot, and I doubt that all of the water would have stayed in there anyways, despite the lid.
I ended up taking about 2/3 of the water, including the tub which held the fish. The remaining water was gravel-cleaned out, sucking up as much muck from the gravel as possible.
Catching the fish was interesting. Some wheren't too bad, but two of the pictus cats got stuck in the net. I had to cut the net to loose them, and on one of them I had to cut a little bit of pectoral fin-spine since it was so entangled and I'd been messing about with it for long enough that I'd rather do that than strees it longer. Lesson for next time: Keep more than one net around, in case you have to cut holes in the first one. And preferrably, use something other than a net to carry them above water.
Once the fish were out, I filled gravel into the buckets. In hindsight, I probably should have split the gravel over four or five buckets rather than three, but I was afraid I'd run out, so I ended up with one going empty... A full builders bucket (15 l / 4 us gal) is quite heavy, especially when you try to lift it to 4ft+ off the floor to pour into the tank...
When we got to the new place, we unloaded the fish first, plugging in the filter first of all, to keep everyone happy. Then we continued to move the tank into place and unloading all the other stuff out of the van.
The "reassembly is reverse of disassmebly" principle holds for fish-tanks:
First I put the gravel back in, and then filled up with the water from the bins. It's a good idea to fill the water carefully, so as not to stir up too much of the muck that is still in the gravel. It's almost unavoidable to not get some clouding of the water.
I matched up the water in the tank to the tub adding some warm water to the tank, and swapped some whater between the tub and the tank, and the started catching and releasing the fish from the tub.
I didn't put all the decorations and plants in as I'd had them before, and it'll probably take some time before the luscious green is back to shape, since some of the plants got a bit damaged. This was hard not to, as some of my plants are of some sort that grow quite long and spindly, and they break if you look at them too hard, never mind trying to get them out of the water... Might have to visit the LFS for some new ones, perhaps...
Finally, I filled up the rest of the water with fresh tap-water as per a usual water-change.
So far everyone seems to be OK, even if they are a little bit shy, and a bit uncertain about who goes where and how to hide suitably. All the pictus cats, including "Short-pec" one was actively swimming around this morning, like they do sometimes, and they all ate with vigour this morning... The cloudiness that was last night is completely gone now.
Of course, if you don't have to move, that's much better option

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Mats