Visiting the UK as a Brazilian and as a EU citizen

My sister in law visited last year from Sao Paulo and stayed for a month, she did not need a visa to enter the UK.

04/21/24 My Brazilian fiancé and I are going through a procedure to get our marriage recognized by the Belgian government.  This procedure requires that she is not allowed to leave the country for 6 months, until there is a reply from the foreign affairs service in our capital.
She hasn't had holidays for more than 1 year now and she can't wait to visit London. But I have not been there since Brexit and it's not very clear to me what we both need to get in, and what it will cost.

Fee    Maximum length of stay
Standard Visitor visa    £115    6 months

Is this correct?

115 pounds per person just for a travel permit, isn't very appealing.
   
    -@Wout

Every indication on the site of the Consulate General of the United Kingdom in São Paulo indicates that a Brazilian citizen  and a Belgian citizen who do not have a criminal record and have not already been making frequent visits to the UK do not need a visa to visit the UK for up to six months fi they meet the eligibility requirements shown on this page:

https://www.gov.uk/standard-visitor

Navigation on the site is not intuitive, and this page only appears several levels down from the "Start Now" button on the "Check if you need a UK visa" page.

If you're still in doubt, contact the British Embassy in Brussels with additional questions.

Visa

Brazilian citizens travelling to the United Kingdom for tourism or business purposes benefit from visa exemption for stays of up to 180 days.  If travelling for other purposes (work, study, internship, volunteer work, family reunion, marriage etc.), the persons concerned must seek the advice of the British authorities to check whether they need a visa, as well as other requirements to enter or remain in the country:

www.gov.uk/check-uk-visa

The same applies to Belgian nationals and passport holders