I have been doing various things to earn extra money over the years; matched betting, surveys, mystery shopping etc. It has been exactly that though - extra money. I couldn't have survived on it solely.
If you are interested in joining any particular survey companies please pm me, I would reommend prolific, swagbucks, populuslive and yougov. There are others that I use too if you're interested.
I also use various apps on my phone - shopmium, checkoutsmart and vypr. The first two allow you to get shopping items for free / reduced price, again I just see this as a nice bonus to help me stretch the budget further than normal.
Lastly I have recently joined Flamingo Paperie (formerly Phoenix Trading). They sell greeting cards, giftwrap and stationery accessories. It is not a get rich quick scheme, it is not a MLM scheme, but it is also not the answer to all your prayers - it's down to you what you put in to it, there are no targets to meet But there are potential financial outlays at the beginning if you choose to hold stock.Some people choose to sell from the brochures, I am selling via craft fayres etc, and therefore I have needed to buy stock. This is fine for me as I see it as a long-term investment, if you are just looking for an employee type work then this wouldn't be for you.
Another option may be something like childminding if your home would be suitable? Could you train and do mobile hairdressing / beauty services / dog walking etc?