I don't get what people don't get about the OP's situation.
Plenty of times people have posted about feeling a bit alone on weekends, with the time stretching out before them. Yes, they can read a book for a while, watch Netflix, go shopping, but actually, doing these things alone whilst everyone else is out with family or children can grind you down a bit.
Even I don't like being alone for more than about 2 days, I get cabin fever and a bit demotivated. I'm like you, OP, I like the structure of work and so need something a bit more structured and not just loll about- that's fun for a day or two not for six whole weeks.
There's been some great ideas on here, but in general, people with families or partners or heaps of friends are quite dismissive of those without those things, and aren't just happy reading a book by themselves the whole time. Sometimes holidays can bring things home to you and loneliness is the modern disease- you are not alone in that, OP, I hope you find some interesting things to do this time around.