Depends when! Summer Easyjet and BMI baby are good if you book early enough, Winter Outbound from Stansted with Air Berlin (book direct) back book a one way through opodo.co.uk ussually around £84 with change in Palma.
Flew Easyjet in June to Ibiza - had no trouble.
Flew Brittania in September and we were delayed for 4hrs on the return. We didn't get back to LGW until 3.30am and then had to wait an hour for all our bags to come off the plane. Nightmare!