can you fit 24T small ring to a 44, 32 set up. i note that the middle ring is engraved 44 32 22 and fear ive made a mistake ordering 24 instead of 22

Yep. I have run 22t, 24t, & 26t without changing the middle ring. Now I run 22t, 36t & 44t which s good for me.

i take it that it has to be a M970 chain ring. i tried another 22T, it wasnt spaced right and was catchin the chain?

I don’t use M970 (XTR) I have the M770 crank (XT) and I have a 22t Middleburn lower ring, 36t M771 Middle ring & 44t M770 Higher ring and never found mixing an issue?

You can use other brands of chainrings with M970 cranks – I’ve used Middleburn – but will need spacers in some cases…

http://www.ukbikestore.co.uk/product/54/cridsd/i-d–outer-chainring-spacers.html