As an Italian citizen, you do not need a working visa for the Netherlands, as it is also in the European Union:
All EU/EEA or Swiss citizens, with the exception of Croatians, are entitled to work without restriction in all sectors and industries.
You just need to register.
The same holds true for the UK, where you need neither a visa nor a work permit.
This is linked to the Freedom of movement to work inside the European Union.