Hi, I have wooden decking and it does get very skippy when wet. I too am looking at replacing it. I’ve been looking at composite decking which is supposed to be non slip and virtually maintenance free, apart from cleaning now and then. There are many types, Deck Trek being one of them. My daughter has it around her holiday lodge and it looks very smart. Here’s a couple of pictures:

My brother has blinds on the windows of his sports club that you can see out of a little and lets in the light but no one can look in. He got them from Blinds2Go an online shop. I’ll see if I can find the name of them.

If you want wooden doors don't let the builders persuade you otherwise. There is no reason why wooden doors can't last as long as you invest in quality doors and maintain them as required. We recommend using a timber called Accoya, which comes with a 50 year anti-rot guarantee and is extremely durable and highly stable, meaning that it doesn't require as much maintenance as other timbers. If you are interested in timber doors still, you may find the below article of interest (it compares the different timbers commonly used in timber doors): https://www.sashwindow.com/how-to-identify-the-right-timber-for-your-windows-and-doors/ The Sash Window Workshop www.sashwindow.com

I know you can get internal secondary glazing, but not external as far I know. There might not be enough depth on the outside.