Tiles

[Jiminy]

can a floating timber floor be put down over tiles?

[Felder]

Short answer;
Yes. If you like the clack-clack-clack (plus echo) whenever someone walks across it.

I'm no expert, but ask your local retailer about re-sealing / re-surfacing the tiles and ask their recommendation about insulation over tiles. It may be more expensive at first, but it will save your sanity.