I don't think there is any problem with grass growing in shade - our garden is pretty shady and the grass still grows. But you might have a problem finding suitable weather to cut it, as it will stay damp longer, and you might also find it gets quite mossy, so you'd be best to use a mosskiller once or twice a year. Apart from that, I think any kind of ordinary mixed grass seed should be fine. If it's for playing on, you'd normally get a mix which includes rye-grass, which is a tough but less pretty variety. Boxes are often labelled things like "suitable for back gardens". Ones without rye grass tend to be labelled for "front gardens" as they are less tough, but are aimed at people who want it to look very neat.