Some very good advice and perspectives in this thread.
You say that work is depressing – is it? Or are you already feeling that way and seeing work as depressing because of it?
As stated before, seem to be far more common than you’d realise, there is a lot of pressure on 40 something males.
From recent experience, if you get to the point of needing professional help (Counselling), pay for it. In my area, the NHS are limited in what they will support, you’ll be on waiting list, and more likely to be part of group sessions. Going direct, I saw someone within a week, 1 to 1 sessions. Yes, the money racks up, but it was worth every penny – much happier person now with a better perspective on life. I went with a specific goal, from the first session, the counselor identified historic issues that he suggested we return to after dealing with the issue I had presented for.
The most important thing is you’ve identified there is a problem.