Thanks for all the helpful advice.

I'm glad to hear that Zebs are hardy fish. I think you're right, I'm confusing price with sensitivity. Last night I put a new Marbled Hatchet, a notoriously sensitve fish, in my 4ft tank. It acclimated just fine in a couple hours.
However, after finding out as much as possible, I think I would feel better putting them in my established 2ft (80litre) tank while their new tank settles. I'm worried about ammonia/nitrite spikes later on. I'm told that using filter gunge and Cycle isn't really enough to keep a new filter stable, but just gives it a little boost. I know when I cycled my 4ft from brand new, it took around 6 weeks to establish the cycle.
So... I will continue to let the new Zeb tank cycle for a few weeks and meanwhile, they can live in the 2ft, which isn't ideal as it's natural gravel which could conceal food, and a UGF which could also pull food into the gravel

but I will do my best to keep it all tidy while the zebs are in residence. Their permanent tank will be bare bottomed, with wood and caves only. I will remove some of the greedier fish from the 2ft so the zebs don't starve! Tonight I will clean out the UGF plate and make sure that's all going well, let the tank re-settle on Friday, and first thing Saturday I will be up with the larks, ready to go collect the zebs

(weather permitting! Snow storms predicted...). I would have got them earlier, but I work full time and can't get to where they are during opening hours... Oh well.
I'm SOOOOOOO excited.