Definitely agree with small steps, and not trying to make massive changes too quickly which will be unsustainable and make you feel as though you’ve failed.
One thing that I would say was definitely worth the money for me is the Nutra Check app (£29.99 for a year, but you can do a weeks free trial)). Helped me a lot to limit some things and increase others - you do have to fill it in honestly though! I haven’t found anything I buy that isn’t included, and you can set up favourite combinations to add quickly. I might not get it right everyday, but the weekly report keeps me more or less on track.
If you’re craving the crunch of crisps, a couple of dry Ryvita make a decent and better substitute.
A ‘pastryless quiche’ is brilliant for breakfast/lunch - I make it with 6 eggs, courgettes, tomatoes, onion, extra mature cheese, various herbs/dried chillies (use any leftovers and veg you like). Bake in the oven until set, then can be cut into slices. Keeps in the fridge for 4 days, but mine never lasts that long - easy to put in a lunchbox and take to work too.
Keep a big airtight container of salad in the fridge - nothing fancy, maybe romaine/little gem lettuce, halved cherry tomatoes, chunks of cucumber plus whatever else you like. If it’s there and ready to eat, I’m less likely to snack. Add a drained can of tuna/slice of pastryless quiche/leftover chicken etc and you’ve got lunch. Boiled/steamed new potatoes keep well too and bulk it up a bit.
Get an egg boiler! I do 6 eggs at a time and put them in the fridge - again, stops looking for other things to snack on and can have with salad, ryvita etc.
When you think you’re hungry, have a glass of water first - ups your intake, and I often think I’m hungry when in fact I’m thirsty.
There are some great links now here that I’m looking forward to checking out properly later (especially the workouts with weights which I really need to start doing). I know joining a gym works for a lot of people, but money is tight or you’ll struggle to find time to go (work, childcare etc) I’d start with the free stuff on You Tube first until you’re confident you’ll actually make use of a membership.
Good luck!