This one was recommended by our diabetes clinic, shows various portion sizes and a fair mix of food types including sweet stuff.
Hiya! I'm also in the UK and while not diagnosed on the spectrum, I have a lot of tendencies in that direction and a lot of issues around food.
The nurse practitioner who did my appointment after diagnosis referred me to the X-pert Diabetes Programme. You could probably also ask for a referral, as they seem to have a contract with the NHS. Annoyingly, their meetings are during the day so I can't go in-person, but they have an online version of the course. It comes with a book as well that has a lot of good information presented really clearly. I bought the book and then was sent one, so I have one spare - if you want to PM me your address, I will be happy to ship it on once school breaks up for Christmas and I have a bit of breathing space. (I'm a teacher and it's INSANE right now.) Otherwise it's available on the site: https://www.xperthealth.org.uk/ The programme also comes with a certain number of minutes (I can't remember how many) with a 'health coach' - I set up a meeting when I was having a bit of a crisis, then got over it, but kept the appointment (which is done over the phone). She was really helpful and gave me a lot of good advice.
She also recommended a book called 'Carbs & Cals' that is really good at showing how many carbs & calories different foods have. There is an app too. Here's a link to the book: https://www.amazon.co.uk/Carbs-Cals-Carb-Calorie-Counter/dp/1908261153/ref=sr_1_1?keywords=carbs+%26+cals&qid=1639089464&sr=8-1
I've managed to put myself into diabetes remission over 3 months by doing things like mashing cauliflower instead of potatoes (I put a lot of garlic, pepper, and nutritional yeast - gives it a cheesy flavour in it which hides the taste), making stir-fries without noodles, swapping white pasta for the kind made out of edamame that they sell in Holland & Barratt, eating lots of seeds, nuts, and peanut butter (the Whole Earth kind without added sugar). I have 2-3 clementines a day, as they (and satsumas) are lower carb than bananas and apples and not as expensive as berries. I also take a vitamin supplement.
Good luck to you!
You might find Carbs & Cals useful - it's the book my NHS diabetic nurse told me to get when I was diagnosed: https://smile.amazon.co.uk/Carbs-Cals-Carb-Calorie-Counter/dp/1908261153/
They also do a recipe book, although I haven't tried it.
Generally, if you're trying to watch your carbs, keto recipes can be good - even if you're not doing a full keto diet. It's popular, so there are TONS of recipes kicking around the internet. There are also several subreddits for it.
Note that there are two different diet factors here: if you're worried about weight, then presumably you're thinking about reducing calories. But to lower blood sugars (if yours are high), the key thing is carbs. Of course you can do both (and if you reduce carbs without changing anything else - e.g. just try smaller portions pasta/rice/potato - you'll reduce calories as well)
One more thing: try not to let health anxiety overwhelm you (easier said than done I know). If your blood sugars come back healthy, then try not to obsess. Of course being a healthy weight is always good, but it sounds a bit like you're going to be constantly worrying if diabetes might develop, and that doesn't sound like a fun way to live.