Mike,
Gridwatch is a good indication of leccy generation types. Coal fired generation has been zero on numerous weekends over the summer.
But hydro output is also shown. Many smaller hydro plants run at reduced capacity because the income is higher than running at maximum possible (they get bigger subsidy payments if below a certain power – stupid, I know, but fact!)
And they are not building any more rivers, either – again most of the hydro is from smaller almost run-of-river sites, where the head is not particularly high, I believe.
There has been a scheme proposed, which would cost billions, to provide storage for umpteen gigawatt hours of storage, so that more renewables could be used to pump water to the installation as an energy storage medium….
They are putting in some new hydro above Drumnadrochit using some of the water which would go over the Divach Falls, I believe. Seen the access tracks but I can't remember the size of the generators. So, yes, they are installing extra generation, where economical and when funds permit.