For anyone needing to apply for a visa to travel to or work in the UK the relevant information is all available on gov.uk: https://www.gov.uk/browse/visas-immigration and here: https://www.gov.uk/government/organisations/uk-visas-and-immigration
For specific queries you can contact UK Visas and Immigration here:
Contact UK Visas and Immigration for help – GOV.UK (www.gov.uk)
or contact an immigration advisor and the UK government provides information on where to find one at the following:
Assistance is also available at the UK Visa Center for persons who need support with getting a UK visa.
There is a UK Visa Centre in Milan whose contact details can be found here: https://www.gov.uk/contact-ukvi-inside-outside-uk
More generally, information for visitors to the UK including what documentation should be shown at the border can be found here: https://www.gov.uk/guidance/immigration-rules/immigration-rules-appendix-v-visitor
For additional information you can contact BCCI member C.A.V. (Centro Assistenza Visti) which provides dedicated services in preparing and filing of visa requests.