I know when my blood sugars are low at night..
I know when my blood sugars are low at night because I will typically have long and very vivid dreams, rather like a fever dream. That having been said, it's hardly a scientific method and other non-invasive techniques are available. The problem with *those* is that the DVLA only recognise a fingerprick test as being accurate enough for driving, so you are stuck with those anyway and it's likely your GP will only pay for one testing method.
Test strips are expensive in the UK - *retail* can be about £25 for 50 strips although the NHS gets them cheaper. This means that many people with diabetes being treated with (for example) metformin or sitagliptin don't get test strips prescribed (or only in low quantities) which seems to lead to poorer overall control of diabetes compared to insulin-dependent diabetics who need to test several times a day. A reliable and inexpensive continuous glucose monitor would be an enormous benefit to many people.