Trees in flower

Immediate disclaimer here that I know very little about tree identification and much as I enjoy looking at them there's no certainty to any of my observations.
Tree flowers are often overlooked especially if they're green or just a bit ugly. We swoon over magnolias and marvel at tulip trees but how often do we wax lyrcial over a few catkins?
I think we start off with sycamore here.

Well these look like rowan (mountain ash)

Oak??

Above, I can't tell.
Below, I can't tell either...

Above, they look reminiscent of pubes so no wonder they're not talked about much. Ash, of some sort?

Below, guessing some kind of salix (willow)

I think it's a hazel?
Well, none the wiser but much satisfied by having seen so many flowers I hope you enjoyed today's offering.
Take care,
Sophie