How long would it take to tile a 9m x 9m bathroom floor.

Wow you are a lucky chap 81m2 bathroom floor:-)

This is a huge bathroom! Size of tile and required preparation is needed to answer this.

are you sure your bathroom is 81m2

First thing is, how easy it is to pick up existing stuff off- it can be 1h or whole day. Main thing is how flat and levelled is the floor, do you need to put levelling? compound to straighten it- allow 4 hours for it if room is not square allow more materials and time for cats depends how many obstacles is to tile around, normal square you looking 6 hours to lay and next day grouting few hours obsacles?... radiators, corners revils... cheer up there are few good tilers around