It completely depends on your layout… if the strip is going in a large enough recess then you can tuck the module and transformer up there as well, at the end of the strip.
If you’re tight for space next to the strip then you might choose to put the module and transformer behind the switch on the wall, in which case you’ll need 5 core wire to go between the switch and the strip.
Either way you’ll need wire to go between the switch and the light location… be it for the 5 core RGBW wires or the 3 core switch wires.
But you noted in the first post you’re using an electrician… he’ll have suitable wire in the van I’m sure.
Also, that reminds me… you’ll need the switches… 2nr retractable (push to make) wall switches.