I can't see any way a bigger surface fleet is going to help the Germans much. Maybe if they skipped the battleships and went purely with fast carriers and cruisers that might help some. Of course they wouldn't be fighting in the Pacific with its huge amounts of room for carriers to hide and maneuver. And we can't assume that the Brits would keep the same mix of ships if the Germans were building several carriers.
As somebody mentioned up-thread, better anti-shipping aircraft would help. Better air-droppable mines and more of them would be good. I've mentioned elsewhere that a version of one of their bombers specifically designed for ship-straffing might be handy--something like the B24s the US decked out with lots of forward facing 50 cals and used to devastate Japanese merchant shipping and warships up to destroyer-size.
Given the right aircraft and the right training, I suppose that the Germans could try to catch the Brits with a Pearl Harbor-type attack within a day or two of the British declaration of war. Historically the Germans didn't have anything like the capability to pull that off, but given six years to prepare I suppose they might be able to put something together. They wouldn't be able to catch all of the fleet, and I'm not sure they could catch enough of it to significantly alter the naval balance, but it might be worth trying.
Catching almost all of the BEF in Belgium would help. The French were historically worried that the Brits would sail off and leave them in the lurch if the battle got hot, and tried to make sure they always had units between the Brits and any major port. If they had been a bit more successful with that in terms of deployment I could see the vast majority of the BEF getting caught in Belgium--assuming that the redistribution of forces didn't butterfly away the German victory in France some way. Having very little in the way of trained enemy to fight against would have made the German task much easier.
From the point of view of a successful Sea Lion, the Germans could build up larger airborne forces and equip them better, but that has an impact on the quality of their ground forces. Airborne forces burned off good officer and NCO material at an appalling rate. Not burning off their airborne forces in Holland would have been helpful for the Germans.