Welcome to the forum @sunlig, I had written something the other day but then it disappeared as there was a glitch in the system, so let me try again.
You are probably even more confused then when put in your question,
so let me try to shed some light.
First, don't panic. The answer to your question depends what your current HbA1c level is.
If it just above 48, (the threshold for being diagnosed with Diabetes T2)
you might only need small adjustments to your diet.
It will take more, if it is above 100 like when I was diagnosed
(and it took me five years, but that this not for here).
Most importantly, get a blood sugar (BS) metre.
While the HbA1c value measures average sugar levels over 3 months,
BS monitoring allows you to figure out what works for you.
Best to measure in the morning, before and 2 hours after meals
Unfortunately NHS usually does not provide meters,
people can link you to affordable strips and meters.
Don't fret over one measurement a bit high, table them
and you will be able to see a trend, hopefully going down.
If so your next HbA1c test will almost certainly be lower.
Diabetes T2 is often called a dietary disease. There is more to it,
of two people eating the same and having the same weight, ... only one might develop T2,
That said many people have brought their blood sugar levels down
with a change in diet, some even in remission.
Find out how your body treats food, there are many books,
one I like is the Diabetes Code by Jason Fung,
here is my summary
https://www.diabetes.co.uk/forum/threads/low-carb-high-fat.172165/page-4#post-2224940
but best to read up yourself.
While people here argue fervently about low carb versus plant based diets
they would probably agree on more than they would admit.
Sugary drinks like coke, ... are bad really bad for us.
They make us addicted. When I got diagnosed I went cold turkey on sugar drinks.
What people know less is that this also applies to fruit juice,
A glass of orange juice can contain up to seven oranges.
You wouldn't eat seven oranges in one meal, so this went as well.
You will need to convince yourself what is required for you
to control your diabetes, we are all different,
what works for me (intermittent fasting)
might not for you.
I hope this is useful. Feel free to ask further questions.
most people on this forum are very friendly
I wish you all the best on your journey