The fully vaccinated and under 18s will no longer have to self-isolate when they return to England or Scotland from amber list countries from 19 July, while FCDO advice has also changed for all three countries, prompting the operator to ramp up.
The operator had previously cancelled all holidays where the FCDO had advised against all but essential travel.
A spokesperson confirmed increases to Spain included the Canary and Balearic islands. She declined to say how much capacity had been added, saying only there were "thousands" more holidays on sale.
