No room to take a student(s) in? If you're near a big town there are often ads in the papers wanting lodging for foreign students and it pays well.
Or have a lodger Monday to Friday (type Monday to Friday lodgers into Google). The good thing about this is that you get the house to yourself again on the weekend.
Any of the large secondary schools in the area looking for exam invigilators?? It is pretty boring but pays well and is only seasonal.
Something you might think of is a company like Universal Aunts where you live in with a person who needs company/some help for a set period of time while their family has a break. It pays very well, your food is included and you won't be running up bills for gas, electric etc while you are there. The downside is that generally you only have 2 - 3 hours off on the afternoon, but that is quite doable for a couple of weeks at a time.
And finally I did house sitting/ cat sitting but it pays very badly.