IOTL the Americans didn't start building new destroyers until about 5 years after the British because they had large numbers of brand new Flush decker type destroyers.
None of the 4 Leaders and 40 V&W class cancelled in November 1918 will be laid down before the beginning of 1919 at the earliest and they would probably be built at a slow rate so that they don't complete until 1924.
IOTL the 9 A class were ordered in 1927-28 and it is probable that no new destroyers would be built until 1932-33 or so. Firstly Parliament would not pass the estimates and secondly the Admiralty would probably want more cruisers or battleship modernisations instead.
A flotilla of A to I type destroyers cost about £2.9 milllion or enough to buy 1½ County class cruisers or twoish Yorks or Leanders. Therefore I think 5-8 extra cruisers would be ordered in the 1927-31 programmes instead of destroyer flotillas A to E.
Though if you want more V&W class destroyers just build more of them instead of the S class by saying that the Admiralty did not decide to design a destroyer for operations in the southern North Sea.
When I wrote that I forgot about the tonnage quotas of the 1st LNT. If more cruisers are built instead of the first 5 flotillas of A to I class more of the older cruisers have to be scrapped so the RN might end up with fewer cruisers in September 1939.
The only way to achieve a one-to-one replacement of cruiser hulls would be to build Arethusas, which has the bonus as they are just cheap enough for 2 to be built instead of a destroyer flotilla. Therefore the RN could buy 10 Arethusas 1927-31 in place of destroyer flotillas A to E.
The 10 Arethusas would displace 10 C class cruisers. In the real world some of the C class were converted to AA cruisers. ITTL the money spent on them would be used to convert an equal number of D class cruisers in their place or more AIR refits of V&W class destroyers.
BUT
Not building the A to E classes saves about £15 million over 5 years. That money would have been better spent on building aircraft carriers to replace Argus, Eagle and Hermes, which was allowed under the Washington Naval Treaty.
The Admiralty did prepare a plan to order fleet carriers in 1924, 1928, 1931 and 1934. Only one was ordered, which became the Ark Royal.
Therefore I think the money should be spent on 3 Ark Royal class carriers to be ordered in 1927, 1929 and 1931. That would absorb £12 million. The ships they replaced had smaller crews and air groups so the remaining £3 million would be needed to pay for the extra men and aircraft.