Insulation/soundproofing for internal stud walls

[J40ADF]

I'm in the middle of prepping our family bathroom. To save time chipping off the old tiles I cut the lot out, plasterboard too. I've binned the insulation that was in there so I'm going to replace it when I close the walls up.
Question is, what thickness of material do I use. The stud is 60mm thick, can I cram 100mm thick material in as I can only see 50mm or 100mm thickness in Wikes at the moment

 

[endecotp]

Other suppliers are available, e.g. at random:
http://www.insulationshop.co/60mm_superglass_multi_acoustic_insulation_roll.html
http://www.insulationshop.co/60mm_knauf_earthwool_timber_frame_party_wall_slab.html
http://www.insulationshop.co/60mm_rockwool_prorox_sl930_formerly_known_as_rw3_slab.html

You might find it difficult to squash 100mm of the higher-density acoustic material into 60mm. It would be easier with the more lightweight non-acoustic insulation. But why bother; just buy the right thickness!