Steve,
Im guessing the floor tiles were porcelain or some stone, you need diamond tipped hole cutters for this job, 365 drill as advertised on this sight will sort
you
6mm x 2 (robe hooks, mirrors etc)
8mm x 2 (shower frames, shelves etc)
16mm x 1 (sink feeds, radiators)
30mm x 1 (bath feeds, taps, body jets)
40mm x 1 (sink waste, shower heads)
Free drill plate (to steady the drills)
Full instructions on back of each packout.
Beat that for £39.99!! give them a call and get them delivered.
Hope this helps mate.
Caledonian.