Concentrate on cross country flying and instrument flying, thats the foundation of professional public transport flying-aerobatics and sea plane ratings arnt much use for flying out of Heathrow. Master situational awareness while instrument flying, you need to be able to enter a hold correctly at any time, any place. That and NDB letdowns catch a lot of pilots out in the simulator and on interview check rides. Master all that at the hour building stage and it will make your career so much easier