Polo GI...

unfortunatley i have cottered cranks so im stuck with 46 teeth up front

therefore 22t isn't ideal as it only 11 skid patches
23t is 1 skid patch
24t is 12 skid patches (not bad)
but by far the best is 25t with 25 skid patches and 48.5GI

so thats why i'm hunting down a 25t

You'd be better off replacing the cranks. I've not ever seen a 25t sprocket. Although I'd never seen a 24t either until I found mine at a jumble.