Well done OP!
I am a couple of years ahead of you and with a much lower D.C. pension.
It feels different, and yes less secure, to not be earning an income, and the finiteness of it: what you have is it, and will only deplete.
But you will definitely be ok unless you have very extravagant tastes and habits.
On £40k income you will probably be able to save especially once you get state pension. A fund for next car, boiler, house maintenance.
I have time and flexibility to get good deals: cheap theatre tickets, off peak train deals, cheap cinema tickets. I go to the gym, swim, walk, go camping, hiking, and am part of a political campaign.
I am not prepared to be tied down by the needs of a dog and the restrictions that dog ownership brings. Or any regular commitment to any volunteering.
See how it feels and how it pans out before making any big changes, commitments or decisions - just relax and enjoy yourself.