A cup of tea in a good flask taken out to enjoy the fresh air on a bench!
A good book you've not read for ages, snuggled on the sofa with the window open listening to the outside.
The cheap cinema midday tickets to a film to watch on your own (and most let you take your own snacks too!).
I love a drive in the evening, a portion of McDonalds fries and a milkshake eaten in my car when parked up at the beach (location dependant obviously!).
As above, just any time spent at the seaside listening to the birds and waves. A bag of chips (bloody inflation it's now £3 ish a bag!) and a good book.
Tesco flowers - the roses (£2.50 and £3 bunches) are fabulous, last forever and really brighten up a room. If the budget stretches to a florist arrangement then that's fabulous too, but the lovely roses in all of the bright colours really bring me a bit of cheer.
Getting up in the morning and not looking at your phone for the first hour - a shower, face mask and blow dry. Cup of coffee and some toast with all of the time in the world to enjoy, zero screen pressure.
Free YouTube yoga workouts (the easy mindfulness ones!) bring a sense of peace and wellbeing to me, and there's all sorts of meditation ones too if you want some zen.
The biggest thing is less phone time (ironically typing this on my phone 😂) and it'll calm your mind without information being thrown at it through a tiny screen.
Baking a cheeky mid afternoon cake! I made banana today and I felt like nigella, eating it made me so happy and looking at it makes me proud - ridiculous as it's just a banana bread, but it's therapeutic, delicious and homemade. Ditto for simple bread making! The supermarket mixes are fab, especially focaccia. It's fun to make and tastes amazing, sparks enough joy in me too!
Sorry to hear you're going through such a rough time, hope your DHs treatment goes well and you manage to find a bit of joy in every day 😊