I came across three visualisations of the present and recent power use for the UK (or, actually, I think, for GB, as Northern Ireland might be a special case) which includes international power imports and exports, and gives the mix of power sources, and how much carbon is emitted.
“GB National Grid Status” has a lot of dials and graphs, in slightly small fonts, for present and recent use.
“National Grid: Live” has line graphs and pie charts and tabulations in a simple readable page
“Electricity maps live 24/7” has a map of Europe and shows international transfers, and colours each country according to carbon efficiency. (But much of the data is “estimated” from models.)