Wet inside of roof / wet felt?

I get a lot of condensation (i think it's condensation) on the inside of my loft roof (tiles on felt). I say condensation as it seems evenly spread throughout the roof. The loft space (height) is low.

Anything in the roof for a few weeks will get spots of water. The wood all looks fine, there is one area with some small white growth on the felt at the very top in one area.

I started look at the loft as one of the bedrooms has a damp corner in the cieling / wall area which I though was a gutter problem but cannot see a problem there.

Is this amoutn of condensation normal?