You sound so sad in your posts, I'm sorry you feel like this. [hug]
On a practical level, I think it's great to take small steps at a time rather than trying to radically change things. Building something into your daily routine (walking at lunchtime, or in the evening after dinner) will soon become the norm. Could it be something you do with your DH or a friend? More enjoyable perhaps then putting the pressure on yourself, and you can have a nice chat and a catch up.
I see that you don't want to spend too much money. I would say to please make sure your trainers are properly supportive - trying to work out in trainers not fit for the job is only likely to end in injury. Going somewhere like Sports Direct is not a good idea, but Decathlon is a good shout, or an independent sports shoe retailer will give you good advice and be able to show you a range of prices. You can also (once you find the right shoes for you), buy previous versions online cheaper.
If you're ready to get sweaty, there are so many workouts you can do at home (but you do need to be so careful about your form, so if you can, look in a mirror to see if you look the same as they do on YouTube). I really like Fitness Blender, which has hundreds of different workouts for free which you can filter to different muscle groups, calorie burn, difficulty rating, etc etc. It would help to have some hand weights, but initially you can go without and see how you're getting on. eBay would be a good call for cheap secondhand equipment. Joe Wicks (the Body Coach), also has loads of stuff, and if you're really keen, does a 3 month programme of exercise and diet for about £100. I've got friends who've done it who look incredible, really lean. He also has several cookbooks which have simple recipes, but tasty food (eg steak with cream and spinach. Not exactly rabbit food, right?).
Best of luck, do come back and let us know how you're getting on. The hardest hurdle is getting out the front door (or setting up in your living room), but you'll never regret the workout x