Ultra-long dated bonds would be a very tough sell in an inflationary world too. Even when the Russian situation and supply issues are sorted, decreasing short-term inflationary pressures, longer-term drivers like the road to net zero and deglobalisation will keep inflation higher than than the last 10-15 years.You could borrow it on long term bonds. We did 100 year bonds for the borrowing related to fighting WW1. Obviously the record low borrowing available over the last decade of Tory rule has ended so I am not sure of the exact extra costs involved.
No idea how you'd renationalise Utilities without either being fleeced or becoming an international pariah to whatever degree.