The Digest of UK Energy Statistics (DUKES), table 5.11 has data for all major generators in the UK, including their location (as one or more of OS reference, post code, or lat/lon), their rated capacity, and their commissioning year. This is a richer dataset than I have seen collated by ppm for the UK. What it misses is IEC codes for the generators, which would require some geospatial matching to be able to match the power plants to other datasets (e.g. ENTSO-E data).