I doubt that anyone knows the exact effects of the planned action at this time.
The Gatwick website says:
"Industrial action by Spanish air traffic controllers is scheduled to take place on 8, 10, 12 & 14 June. This will cause delays and cancellations to flights to and from Spain and other European destinations. Please contact your airline for up to date information about your flight."
easyJet (which operates the 0600 Faro service) says:
"easyJet has been advised of planned industrial strike action by Spanish Air Traffic Control services on 8, 10, 12 and 14 June for two hours each morning and two hours each afternoon.
At this stage easyJet plans to operate its full schedule, however, like other airlines, some flights operated during these periods might be delayed.
We recommend that all customers flying to or from Spain on 8, 10, 12 and 14 June check the status of their flight on our Flight Tracker page before going to the airport.
We would like to reassure customers that we are doing everything possible to minimise any disruption as a result of the industrial action."