I'm still on the Libre 1 so I can't tell you about Libre 2.
For me, as a type 1 on insulin the Libre has made my life a lot easier, but a lot of this is because it allows me to react quicker with insulin or food to highs and lows. I have been self funding for years before finally getting them covered by insurance, and yes, it's expensive and I'm not rich.
For a T2 not on insulin it can still have a lot of advantages by enabling you to see trends in your blood sugar.
For me, they read lower than a simply glucose meter, which is very annoying, but it's still worth it for me.
You can always try one as a one-off, you only need a smartphone to read a sensor. It seems they are handing out free samples now in the UK, but I have no idea how this works for Guernsey:
https://www.diabetes.co.uk/forum/threads/libre-2-sensor-free-trial.180199/#post-2372664
Alternatively, if you want to buy over the counter, they're cheaper in France than they are in England.