I am hoping to bring out figure sets of the above.I am having some ptoblem in getting good images of the uniform detail.I particular the of what they carried on their backs,rucksaks etc,also the type of water flask,some images show a typical British one others a much larger "rounded one.
I am sure you meant Indian Army rather than just Sikh's because "Sikh's wore turbans", most of the Indian Army wore them at the time, as shown here. These other links should give you some good material for the uniform and equipment of the Indian Army during WW1:
I would suggest that the same figures, without webbing and weapons, would also make good men for Indian Labour Corps figures. Some Chinese Labour Corps figures would also go down well!