The current rotors on my nc21 are fixed, are there any issues with swapping these for floating/semi floating ones? Probably a silly question but would rather be safe than sorry

You would have to ask why? fixed are no issue for a bike such as the NC21 (or RC24s and CBR600F1) etc..

You are intending to upgrade to NC24 rotors?

There isnt much benefit but you should measure your original discs.

Depending on which model of NC21 it is it might have 255mm discs... the NC24 rotors are 276mm.

I cant remember offhand but i think the mounting points between the NC24 / NC21 forks are the same, if they are then you would just need the NC24 calipers and mounting brackets, or even just the NC24 caliper mounting brackets to make use of the 276mm discs.

Thankyou for your help thinking i will leave thsm for now may play around later