Re Cruiser construction.
One possible way of saving money could be to decommission/disarm the C/D class cruisers prior to WW2. As these ships were really of limited use with a short range and even when turned into AA ships they had little more firepower than a destroyer at the cost of far larger crews.
If you want to save cash, scrap them, put the guns ashore somewhere and be done with it. The more expensive option would be a conversion into CL-AA's.
Strip out the torpedo tubes and 6-inch mounts and fit dual 4-inch mounts and any single or double 2lbers and Vickers .50's you've got. Add some extra fuel tanks if you can. Whilst basically you'll have a large Black Swan with 8 x 4-inch guns and some 2lbers its better than what the RN has for the most part. But this is the expensive option and crew intensive too.
Perhaps scrapping ALL 22 is too extensive but you could get rid of 50% of them for scrap and put their guns ashore and then try converting as many as possible into CL-AA's to escort the Dreadnoughts.
One thing to also try getting the RN to do is standardize on a gun caliber for their DDs. The RN spent a LOT of money designing different turrets for different guns of the same size but varying calibers. There was loads of 4, 4.5 and 4.7 inch guns of varying caliber. Settle on two types and stick with it. 4.5 for the bigger more modern DDs and 4-inch for the cheaper vessels.
Naturally the 40mm Bofors is a superior weapon to the 2lber, but this is the 30's and the RN, whilst being very air aware had an overblown faith in the ability of AA guns to deter and defeat an air attack. As this is a doctrinal thing, its going to take bitter experience to change it. And as its the 30's the 2lber mounting (especially the Chicago Piano) is still one of the best AA guns in the world.
For the fleet DD's the J's Ks and Tribal likes i'd go for a DP 4.5-inch dual mount and for the Wartime emergency DD's a single but DP 4-inch mount, basically half one of these
in a DP mounting. The RN stuck with the LA mounts for way too long and if the RN who was in love with the gun as the main deterrent against air attacks in the 20s/30s they should realise that a DP mount is of greater use than a LA mount.