If paprika is used for colour only as seem the case with most mixes do you think I'd be better of using kasmiri mirch.
Hmmm...I'm probably not the best person to ask as I seem to have an inbuilt aversion to the bitterness imparted by kashmiri mirch and it's certainly a flavour which I am not accustomed to in any BIR curries. It certainly adds a red colour if that's your aim.
That said I recently used the MDH kashmiri mirch in CT's madras and that turned out far more palatable (compared to other kashmiri brands I've previously used). So go for MDH if you intend to use it at all. Personally though I'd go for a bog-standard chilli from Rajah or East End though.