Oh Wow!!
Well as a fellow Brit, for you own future success, I advise you to not start slimming world and weight watchers. If you haven't already my advice is to go onto My Fitness Pal App and just start learning about foods, Eat Fresh!!
Try and get into your head that if it isn't in its most natural form (or a frozen state of its most natural form) then it is most likely not good for you. For example: Veggies.... I always use steam bags, I don't have time in my life to keep things alive once ive bought them, and putting veggies in a pot and cooking them takes more time than the pre arranged already weight out veggie bags
. Boiled eggs, Turkey and Fish will be your best friends for life..... You will realise that pork isn't worth the calories lol, neither is butter. If you're a Mayo queen, then I hope you like Salad cream, and I never buy bread anymore, its always the sandwich thins.
Trial an error is the way forward, Use the app to track everything you put in your mouth, weigh every ingredient and be honest with yourself always, even when you fancy a sneaky wee chocolate treat. I eat 1350 calories per day weighing 286lbs or 20st 6 depends on how you wanna see it. That is pretty low for most but personally, I don't lose weight any higher than that unless its been pushed over with a little bit more protein.
You have done amazingly so far, all I can say is Stick to the forums, find a place that is right for you. The 20-somethings page usually has people on it, the challenge pages as well. The 300+ page is for people who have been over 300, they dont throw you out once you get under
join the community, it will help and keep you accountable.