Hi op, I started in the same boat as you. I was actually bigger than you at 20st 8lbs last autumn. I have lost 3 stones since then, and the good news is you don't have to do anything drastic at this stage to lose weight.
I have found the best approach is to make small, subtle changes and add to them over time. Making weekly meal plans and sticking to them is what got me going at the start (and I still do it now), and just cutting back a little bit on snacks. I lost the first 2 stone just by doing this.
Gradually, I started to cut back on the fizzy juice and have squash instead (I don't like plain water and would not drink it otherwise) and started to take fruit into work to snack on instead of crisps. Around this time, I also started to use Slimpod. A lot of people say it doesn't work for them, but for me, it seems to be having a positive effect.
When I got to grips with the basics and lost 2 stone, I then started to think about joining an exercise group, getting more steps in, and here I am today 3 stones down and getting to grips with the exercise before I move into focusing on maybe doing 2 exercise classes a week instead of 1. (Though weight loss is more to do with food than exercise, so I wouldn't worry about that just yet)
The best tool you can use for losing weight is patience 🙂 unfortunately, healthy, sustainable weight loss is a long journey that we need to strap ourselves in for. If we make too many changes at once, we can become too overwhelmed and give up, leading us back to square one.
So my advice is to start small, get your head around healthy meals, and cutting back on snacks first, and then move on to exercise when you have found your feet. It's all about learning to build healthy habits over time so that we get used to them and they become part of our routine without us even thinking about it. These habits need to last us our whole lives.
If I can do it then so can you 😊 good luck, op.