I'm Indonesian passport holder with Italian husband, I have Carta di soggiorno per familiari di cittadino dell'Unione. Can I go to London without Visa?
No you can't. Whether you need a visa for the UK is decided by your citizenship. Being an Indonesian citizen, you need a visa for the UK. Even if you were married to a British citizen, you would still require a visa to visit the UK.
Incidentally, when UK was a part of the EU, technically, you could have been allowed entry into the UK without a visa if you were traveling with your husband, as a family member of an EU citizen traveling with them and having a residence card as an EU national family member. But not now.