Until you find Tamana's! While it is not a vegetarian restaurant, it does have plenty of dairy free curries available in a buffet style setting, the ingredients of each clearly labelled to make it easy for you. Also, no worries about dishes containing ghee (clarified butter common in Indian dishes), their website says..
"TAMANA'S GUARANTEE: All our dishes are cooked in pure polyunsaturated vegetable oil with natural herbs and spices. We use NO animal fats, artificial preservatives or monosodiumglutamate (MSG). All our curries are gluten-free with a selection also dairy-free."
Furthermore, they have gluten free Naan bread.
It's cheap & informal with no table service.. The only thing that lets this place down in my opinion is the overall decor. It's a bit on the shabby side, but they do make up for it with some nice traditional artworks on the walls & delicious food.
Cons: Bit of a shabby feel