Se vai per turismo non ti serve il visto.
NO, in most cases you do not need a visa to come to the UK for a short visit You told us that
- you are a national of Brazil.
- you are coming to UK to Visit.
- you are normally and legally living in Italy.
What do you need to do? If you are coming to the UK for a short visit (up to 6 months), you generally do not need a visa.
However, you should bring documents with you to show our immigration officers when you arrive at the UK border.
The Visiting the UK section describes the different categories of visitor visa, and lists the types of document that you may want to provide. It also explains the conditions of your stay as a visitor.
Although you do not need a visa, you may want to obtain one before you travel (for example, if you have a criminal record or you have previously been refused permission to enter the UK). And you
will need a visa if you want to come here in some categories of visitor (such as a
visitor for marriage or civil partnership). The Visiting the UKsection contains more information.
http://www.ukba.homeoffice.gov.uk/visas-immigration/do-you-need-a-visa/