Why proposed 1941 heavy cruisers would not be ready in 1942

If the war began later, how many proposed 1941 Admiral-class heavy cruisers would be available by 1942?

Probably none; ships first ordered in 1941 would still be under construction in 1942.

The question uses a hypothetical label for a proposed second generation of British 8-inch cruisers. The Royal Navy had not placed such ships in its 1939 or 1940 building lists. If ordered in 1941, they would only be laid down or under construction during 1942. A design discussion or projected class is different from a funded program capable of delivering wartime hulls.