In addition to what others have said...
They take at least a decade to get online.
The so called mini reactors being proposed by Rolls Royce still require an area the size of half a football pitch and still generate the same amount of nuclear waste. And still take at least 10 years
We don't know how to get rid of the waste. At the moment, its bury it or put it out to sea. Where it remains radioactive for 10s of thousands of years, and is at risk of just blowing up spontaneously.
Scotland generated 97% of its own power requirements from renewables last year, a number which could be increased fairly easily with proper investment in all renewables - solar, wind, geothermal, hydro, etc. Then the energy could be exported to different parts of the UK which need it.
At the start of the war in Ukraine, remember when Russia took over Chernobyl and Zaporizhzhia? They are not stable and susceptible to attack.
This is not based on a CND/hippy dislike of nuclear, its based on knowing how it works.