Here's news to me: non-homeowners can house swap too. Well, kind of. Instead of offering a house in return, you offer your time and become a "housesitter". C
And here's a sample ad:
"HOUSESITTER needed near Edinburgh. I need a housesitter for various time periods, but at least one week for my comfortable home located about 10 miles east of Edinburgh. I prefer two people, and don't mind if you are friends, a couple or married. We have two dogs, one horse and one pony, a large garden, and stables. You can have the use of a car if needed, since we are very accessible to Edinburgh and only 10 minutes from hills, the beach, and golf courses. Would love regular housesitters, if possible, to allow us to get away fairly regularly, but don't mind one off's. Our house is on the edge of a small town in a peaceful but not isolated location. The dogs run around the garden and don't need to be walked. Horses need to be mucked out daily, fed three times a day and stabled at night. Housesitter must have experience with horses and dogs."