Indeed they basically had the RN go 'Yeah we're gonna sit this one out for a few days, we're busy sunning ourselves in Scapa.' at the start and then play DUMB when the germans diversion fleet sailed.
The Home fleet wasn't coming south at all, this had been discussed prior to the invasion twice in cabinet and agreed to by Churchill et al. Both Pound and Forbes agreed there was no need, there were 50 destroyers and cruisers in the Portsmouth and Nore command plus 1 battleship and hundreds of smaller vessels. The Home fleet was on the lookout for the sortie by the German big ships, which they didn't know were incapacitated. They also expected an attack on the east coast of England as this was thought the best place for an armoured attack. The Kriegsmarine would have sent out both the
Hipper and the
Scheer just prior to the invasion as well as the "Autumn Journey" feint - all of which was doing what was expected of them. The
Hipper did raid the Atlantic convoys not long afterwards and managed to return (after causing more alarm and confusion than anything else due to the
Edinburgh Castle's sacrifice) . It took the entire home fleet plus Force H to sink the
Bismark.
Also the Luftwaffe was told it could not stop bombing London and must play DUMB, even when the German players said they wanted to bomb shipping instead. They did not have even local air superiority so this wasn't Sealion, it was something else.
The Australian Ninth Division somehow shows up near Canterbury in preference to other, closer units when its components were based in Somerset, and anyway it didn't exist in September 1940 - it was formed as a two brigade division in October 1940.
The kriegsmarine also had to play DUMB and weren't able to try out the combination of channel guns, mines, U-boats, aircraft, and hundreds of escorts of sizes ranging from destroyer to patrol boat.