Well I would have suggested London road too but if you can't find what you're looking for come over to the dark side in Rotherham and go to PAK Supermarket it has hundreds (
and I do mean hundreds) of different spices and you can buy about 250-500 grams of spices for the same price as a small jar of about 50 grams of the same stuff in the supermarket.
Have a look:
http://www.youtube.com/watch?v=lBkcG7PGg1I Off the top of my head they have lots of indian breads, sweets, Star Anise (I know that 'cos there's a packet downstairs I bought from there) fresh coriander, fresh and dried curry leaves, fresh saag,fresh okra, fresh kerala, (although I don't know what you do with them) and lots of other fresh/dried herbs spices I've never heard of, parking's free and it's slightly out the town centre.
I've been there today.
Address: 174 Wellgate, Town Centre, Rotherham S60 2PE
Phone:01709 839980
If you can't find everything you want in there I'll eat one of their scotch bonnets!

Hope that's helpful, Wayne.