If renationalisation is not an option - prevent bonuses and dividends being paid until all leaks are stopped, all sewage is properly treated, water treatment works are up to a decent standard and new ways of sourcing and providing water are brought online - prevent the idiocy of Thames Water actually mothballing a desalination plant in the middle of a drought because the water is too salty sometimes....
Ensure the gas infrastructure is robust enough to store enough gas and prevent it being sold for profit - Octopus, I'm looking at you
Electricity generation needs to be a priority - develop any and all clean (ish) methods of creating energy in order to make us self sufficient
Stop bailing out the privatised utility and travel companies - most are part or completely owned by foreign investors (including foreign governments)
Remove all alcohol from Westminster bars - send any unopened bottles back to the vendors and let the staff take home any opened bottles
Stop subsidising MPs' meals
Prevent MPs from claiming expenses for their first or second homes - no duck houses and no heating the stables
Prevent businesses from hiding behind shell corporations and prevent shell corporations from owning stocks, shares and property
Prevent non-doms from running businesses and donating to political organisations
Make MPs declare where all their funding comes from and declare the financial and political interests of their lobbyists, their advisors, their interns and their friends and families
Prevent MPs from hiring their own family members on expenses
Prevent all MPs from having second jobs and prevent them from being hired by corporations who would benefit from their political connections for at least one year after they cease to be an MP