I was back for 5 months before applying for my Fiance Visa, so I know how it feels.
I didn't work those five months so I spent my time doing crafts, going for bike rides (I was living in a rural area and would go on adventures up the logging roads), taking hikes, cooking yummy food, finding new recipes, growing veg (it was summer and DH did the same), visiting family and spending time in my hometown.
DH and I Skyped every day and regularly sent photos of what we were doing, what we cooked, how our plants were doing and funny things we saw throughout the day.
I also spent a lot of time going through my stuff and giving away as much as I could. I think I gave more to Goodwill than I brought with me! It was easier to get motivated to go through everything after I had sent in my application, but once I started, I would spend 4-5 hours a day packing.
I also spent a lot of time exploring the UKBA website and forums like this to be sure I had everything ready when I came time for us to apply and I knew what to expect for visas down the road.
I know how it feels to be stuck, but if there's anything you've always wanted to do or learn but not had the time for, well...... you've got time now!