Quite a bunch of Dutch and North German zoos have exhibits imitating the wildlife, especially the avifauna, of their shores and the wadden sea-and I remember visiting a tiny British zoo in the 1980s (forgot the name, though) that also had a similar exhibit.
If nocturnal behaviour does not convince as an argument(although I do consider this a strong point), then think of the combination of short life-span, high husbandry efforts and low public attractivity in the case of especially smaller European mammals. European moles f.e. are among the most difficult to keep; see the exhibit design of the University of Kassel on that. And what nocturnal Australian animals are displayed in Australian zoos? Also marsupial moles and Ghost bats? Or rather Bettongia sp. and sugargliders i.e. the same kept in nocturnal houses outside of AUS?
It's all nice and fine if You want to plan an European exhibit for Your dream zoo...However, I have the unthankful job to slam You down to earth: most visitors, including tourists, wouldn't understand and appretiate Your ideas, especially in a city zoo like London. "Red squirrels in the monkey cage? A Hedgehog supposed to be somewhere in that dark exhibit? A weasel somewhere in that exhibit but never visible? What a rib-off! I can have that at home for free"... Some of Your ideas have already been turned into reality by zoos long time ago- f.e. the "Under-the-Earth-Zoo"-exhibit at Dresden zoo (
Unter der Erde )-and they are usually, well - flops; most visitors don't appretiate them, even if You add some funny ideas like a slide for kids down to the exhibits underground. "Europe" as a theme in a zoogeographical orientated zoo can be a good idea, and is therefore often part of European zoos-however, You always end up with the same larger species mentioned before; and that's also due to the low attractiveness and difficult husbandry of local species (I can't think of more than a handful of major European zoos actually keeping European hares, wild rabbits or Black Grouse, not to mention roe deer or Western Green Lizards...).
Most tourists will appretiate Fallow and Red deer, Moufflon and Wisent, Grey wolf and European lynx, Brown Bear and European Wild Boar as well as Waldrapp and White stork f.e. as "typically European animals"-but the only time I saw f.e. an European robin as a zoo animal was in San Diego Zoo (and maybe Lohberg, too).