Hi and welcome.
Firstly, do not be embarrassed or ashamed. I found the TED talk (linked below) by an eminent American doctor Peter Attia to be helpful in my early journey with diabetes....
Secondly, you have every reason to be proud of yourself for losing 3 stone since summer. That is an amazing achievement and just shows that you have the mindset and determination to tackle your diabetes in a similar fashion.
I think there may be more than one thing causing your problems/symptoms and they may or may not be related. Skin infections including yeast infections thrive when your Blood Glucose is high, so that may be related and the tingling can also be due to diabetes, however the dry, itchy skin and possibly the hair loss could also be due to stress or even the menopause or not being properly hydrated. (I recently started on HRT and that has made a big difference to a lot of issues) The most common symptoms of diabetes tend to be thirst and weeing a lot as the kidneys try to remove the excess glucose from the body, particularly when your HbA1c is quite high as yours is, but there are plenty of people on the forum who have brought their levels down from even higher than that, through dietary changes and put their diabetes into remission, so with the right advice and a positive attitude, you have a good chance of doing the same.
The key is to cut down your carbohydrate intake. That is not just sugars (which are found in fruit, fruit juice and smoothies as well as the obvious cakes, biscuits and sweets) but also starchy carbs from grain products like bread and pasta and rice (even those healthy wholemeal varieties) and breakfast cereals, even that wholesome porridge and also potatoes. You might wonder what there is left to eat but it is surprising once you get your head around it.... after all, we have spent a lifetime pilling our plates with carbs, so learning what to eat instead is bound to be a bit mind boggling at first.
Meat, fish, eggs, nuts and mushrooms are all good. Green leafy veg are great. Mediterranean veg are good, oils and fats are good (you need to get your calories from somewhere, if you are reducing your main source of them (carbs) and fats take longer to digest so they keep you fuller for longer) so opt for full fat dairy like wholemilk, butter, cheese, cream and creamy natural Greek yoghurt as these are lower in carbs than low fat options. Cauliflower is your friend.... who doesn't like cauliflower cheese (better for diabetics made by coating the par cooked cauli in cream cheese and grated mature cheese and then browned off in the oven rather than using flour (carbs) and milk to make a cheese sauce. It can also be mashed to replace potatoes and used to top a cottage pie or finely chopped to make a rice or couscous substitute. Courgettes can be spiralised to make courgetti instead of spaghetti and there is a product called Bare Naked Noodles which is pretty much zero carb for use in stir fries etc. Hopefully that gives you some ideas.
I appreciate that the Cambridge Diet has worked for you but I am not sure eating meal substitutes like shakes and bars is ideal and eating real food id definitely more satisfying. Surprisingly, eating fat does not make you fat as we have been led to believe and many people still lose weight on a Low Carbohydrate, Higher Fat (LCHF) diet.
It is also important to increase your activity levels and a brisk walk each day, even if it is just 10-15 mins can help to lower your BG levels.
Finally, many members here find it is beneficial to self fund a Blood Glucose Meter as they are not generally provided to Type 2 Diabetics these days. They are relatively cheap to purchase (approx. £15) but it is the on going purchase of test strips which tots up the expenses and for this reason the SD Codefree Blood Glucose Meter is recommended most often on the forum because it's test strips are one of the cheapest at £8 for a pot of 50. It can be purchased on Amazon I believe and testing before and 2 hours after food will tell you whether your body coped with what you ate or you need to reduce the carb portion in that meal next time. If the rise in your BG is more than 3mmol 2 hours after the meal then you need to modify it. Less than 3 and you are doing well. We are all different in how we digest food and some diabetics will be able to eat more carbohydrates than others, so testing yourself and tailoring your diet according to your readings is the best way to manage it, rather than blindly following general dietary advice from health care professionals, which is often outdated.
Also, if/when you start on Metformin, do make sure to take it mid meal with a substantial amount of food as it has a tendency to cause digestive upset.
Best of luck and feel free to ask whatever questions come to mind. Some of your symptoms may take a few months to settle down (like the arm tingling) provided your BG levels come down. The skin problem may be something else.
Hope the above gives you some guidance. If you read plenty of back posts you will gain a lot more insight.