And thanks to Phil_M too.
I've had a Quick Look and it appears that Instant Commands only work into Snapshots so making PC changes when preset buttons are pressed doesn't seem to be possible which is a shame. It may not be the most elegant way to use the Floor but my setup really only uses single presets for any given tune. I use switches to make step changes and assign parameters to the expression pedal and that's it really.
On a preset by preset basis this is fine as each is very different to the others but no that dynamic.
The issue is that should one preset have a particular, say, heavy reverb or other effect, and the next, using the same box, be more subtle, the preset change will leave the former and not the new effect in place. With the controller I could change presets and simultaneously change the external parameters.
I can't currently see a way of doing this with the Floor which is a shame.