Andy
It IS possible, but it's still very rare. Out of over 100 pump users in my PCT area I'm the only one with permanent funding, so I know I'm extremely lucky. But I have zero hypo awareness so in other respects I'm extremely unlucky! The sensors are expensive (£40 each), and not reliable or accurate enough (yet) to warrant their funding for all. Having said that, I wouldn't be without mine, just for the hypos I manage to avoid even though it doesn't catch all of them.
One way to proceed is as I did, via your PCT's Exceptional Funding Panel. You will need the full support of your consultant, in fact it will be him/her who makes the application on your behalf. Some clinics provide CGM on a temporary basis to sort out specific control issues, and sensors are sold in smaller batches for exactly this purpose (boxes of 3 vs boxes of 10). But on limited budgets, clinics want to ensure they are getting best value out of the systems they allocate, even temporarily.
Let me know if you want any more specifics, feel free to PM me.