Skip the Fulmar, threaten the future Sir Charles Fairey with nationalization of his firm if he persists with his Fulmar folly and force him and Vickers-Supermarine to get making Seafires. Will this be a detriment to the available Spitfires for the Battle of Britain? Perhaps, but the Seafires can join in the fight as well.
Now we're talkin'... The decision of the Air Ministry not to issue the FAA with a single-seat fighter specification in the early to mid 1930s time period had enormous repercussions. That doesn't mean that US naval aircraft shouldn't be purchased if the Brits did get Seafires earlier. The more the merrier, but the pressure to get hold of decent carrier based fighters would not have been so high as they were in the first few years of the war.