On the plus side, when you are in Portugal, and two days before return to UK, you can simply walk in and take a rapid antigen/ nasal flow test (ask for Fit to Fly) at almost every Farmacia for EUR25. I did this in Principe Real and 30 mins later had my email sent to me with name, date and name of lab, all of which were ok for airport and airline staff in Portugal (on departure) and on arrival in UK.
