There are 3 options, presented here
http://www.finnair.com/GB/GB/informa...business-class
You can pre-order in the manage my booking (but sometimes website just doesn't work and you need to call to make the pre order)
I think you can find some reports on FT about the meals.
If you skip this pre-order, there is the "normal" 3 options onboard, so all in all 6 options of main course.