Welcome to you too. I too was just letting it slide, and living in self denial, until my HbA1c was up to 66 in March this year. I was overweight, had high blood pressure and hardly ever exercised. Now I've taken control and gone on the LCHF diet, lost nearly 20kg, go to the gym every day and run a 5k. My last HbA1c was down to 38, and I expect it to be possibly even lower when I go back in a couple of week. I've stopped taking medication for high BP and statins, and cut down my Metformin to 1g per day. I had a hiatus hernia and was on meds for that but that's gone and I was getting knee problems which have also gone. I sleep better, feel much happier and that's affected everyone around me.
I'm not (just) gloating - the first step is to decide that it's YOU that is in control and don't accept the official position that type 2 is a degenerative disease and you'll need to take increasing amounts and types of medication. If you're like me and most diabetics I know, you'll have been told some non-specific thing when you were diagnosed about diet and exercise, but hardly more than that - It's quite refreshing that you've actually been referred to a weight loss programme, though I too am somewhat skeptical about slimming world.
I personally don't like plans from these commercial organisations who are mainly about selling you stuff, and slimming word stuff is full of carbs, which will spike your blood sugar, and though losing weight in the long term might well have the effect of lowering your BG, you can do that almost instantly by eating a low carb high fat diet. Don't worry about the 'high fat' - it's not that high and study after study has shown that if you eat the right mix you won't necessarily raise your cholesterol by eating it. It's not 'high fat' that's the problem, it's a lack of the right kind of fats - Omega 3s will lower your cholesterol, so you can eat bacon fat, cream and eggs without any problems if you are eating enough nuts, seeds, olive oil and oily fish.
There's plenty of advice and recipes on here and around the rest of the internet. There's a lot of crossover with other similar diets, the Paleo diet (though the principals of that are a bit daft), the Mediterranean diet (if you can find a simple definition) and to some extent Atkins, but that includes more protein and might not be as good for BG control. For a start I'd suggest cutting out bread, cake, and other large amounts of carbs in your meals, such as rice, pasta, potatoes, and eating more veg in their place.
