Cheers Eric for the new script.

In the end I queried the ring buffers and found that SQL Server had more RAM assigned to it than it currently needed, and the OS was suffering. (last year it was the other way around).

Amended the Max memory so that the OS  wasn't starved and everything seems to be performing better.....at least for now.

Below is an example of the blocking issues I was getting

And this is after I adjusted the memory allocation