The problem of a large British fleet early is twofold:
1. Sea-lion much harder for Germany. Germany would not have the funds to build warships, transports, and troops to do Sea-lion- not to mention build troops to guard against France/build up for Russia; when all Britain has to do is build troops (upgrade IC possibly as well).
2. Earlier Allied landings in Europe/earlier pressure on Italy in the Med. Italy would have a tough time if Britain has a larger fleet to contest the Med- in addition the French and British can consolidate their fleets- then the British can make landings in France, Norway, Africa, Italy way earlier than was previously possible.
Unless of course you are proposing the British start with an ahistorical shell of a fleet.