As mentioned this deal is available throughout whole year 2015 with no further restrictions. Max stay in Brazil 3 months. All these European cities are easy to reach either by bus or low cost airlines. To check your connection possibilities from your home town directly you may check through Skyscanner. Cheap accommodation in Sao Paulo is possible to compare and book here.
Booking samples
Amsterdam - Sao Paulo - London for €436
Amsterdam - Sao Paulo - London for Ł339
Brussels - Sao Paulo - London for Ł340
Amsterdam - Sao Paulo - Frankfurt for €463
Booking sample of cheap open jaw flights Benelux - Sao Paulo - London/Frankfurt for €436 here. In this case you would be flying from Amsterdam Sao Paulo on 7th of July and returning from Brazil back to London on 24th of July 2015.