Roof lantern

[Cupcake77]

We are currently in the process of a kitchen diner extension 5m x 6m. We are hoping to have a roof lantern as a focal point and to let in more light.

I don't want it to look too small but at the same time I need to think about the more glass, the harder it is to keep warm.

What size lantern would you go for, for that size of roof?

Many Thanks