Hi, and welcome!
High BS, so don't test? That is kindof like saying, "Close your eyes when clossing the street.". Doesn't make sense, does it? Bottom line, teststrips are expensive, and NHS doesn't like paying for them. We've heard a thousand different excuses here, but far as I know, that one's new. So, you're going the low carb route, but you're still flying blind. As we're all special little snowflakes (everyone's insulin resistance, insulin response and liver dump is different, making a diet always highly personal), you won't know what certain foods do unless you test. For the bulk of us, even "brown" carbs are a no-no. That might be different for you, but you won't know unless you test, test, and test some more. (Before you start eating and 2 hours after first bite. If your numbers go up more than 2 mmol/l, the meal was carbier than your body could handle. Some would say test an hour, two hours, and three hours after the meal, but that makes for a very, very expensive day, as a self-funder. Though it might be worth it at the start though). Once I knew what foods did what, I felt a whole lot more at ease and could reduce testing dramatically. So it won't always be an arm and a leg.
As for Metformin... I don't quite see how they could even risk putting you on that when there's Colitis Ulcerosa already present... Even if you didn't respond badly to it, its potential to make a bad situation worse is just... Not worth it, in my opinion. (And it IS just my opinion. But a friend of mine had it, so I've seen rather up-close the misery it can cause without being aggrivated by something else). I know what Metformin did to my intestines, I can only imagine what it may be doing to yours. The good news: If you go low carb/high fat, the meds could well go out the window. Metformin does make a little difference, but it doesn't hold a candle to what a change in diet can do.
I don't know how willing you are to ditch or reduce carbs even further than you already have? Add in fats and protein to keep from starving all the time? I'm at about 20 grams of carbs a day right now and my bloodsugars are fine, non-diabetic. In spite of having sinusitis and an inflamed tear duct right now, which should've sent me into double digits bloodwise, but didn't.
Foods like this would help: leafy greens, above ground, non-starch veggies, eggs, full fat greek yoghurt, berries in moderate amounts (other fruits are too sugary), cheese, olives, proper, real butter, fish, meat (bacon is about to become your best friend, potentially), avocado (which I now realise is also a fruit, but what the heck), and I have to say, cauliflower rice is versatile enough to take the place of some other foods. On our table it has replaces rice and potato, in any case. I have extra dark chocolate almost daily, nuts too...
KFC is fine if you peel off the crust. And heck, I started going to McD's and BK again once I found out a burger is low carb if you leave off the bun! (Around 5 grams of carbs opposed to almost 30 to 40. People taking your order won't even blink at the request, so no worries there. Add extra bacon and greens to make it a little more filling, and Bob's your uncle!).
Your eyeproblems came fom high bloodsugars. Glocose ends up in your eyes, and distorts vision. Your brain makes corrections for it, so when you start dropping, it has to correct all over again as the glucose leaves your eyes. So no worries, it's normal.
And anxiety often gets worse as bloodsugars rise. (As does depression, emotional instability and what have you.) I've been a non-functioning wreck my whole life, but with my bloodsugars under control I have fewer panic attacks, and they don't last as long when they do hit. So you might feel a change in that too. Not too scary, eh?
Good luck!
Jo