It sounds like those numbers are in mg/dl which is the same format we use here in the US.
To convert mg/dl into mmol/L (UK measurement) you would divide by 18. So your reading of 337 mg/dl would equate to 18.72 mmol/L.
While all of your readings are high (although your readings under 200 are very close) that's not the worst thing in the world when you're first diagnosed. It's perfectly normal to have high blood sugar in the first few weeks after your diagnosis, and I'm actually surprised you've already gotten them that low with just your morning 14u of insulin.
Eventually, your doctors should start you on a basal/bolus insulin which means you'll be able to get those numbers much lower, but for now, keep doing your best.