Saying that lack of hangar on a ship operating in arctic waters is "less than suitable arrangement" is a very nice euphemism.
As for the AA - my guess (but for a date slightly later than 1939) would be to remove two pairs of the 4-inch guns on sides (retain only first and last pair). On the sides of the bridge and instead of the 4in under the catapult put 20mm AAAs and the pair of 4in between the funnels replace with (elevated) position for 2 quad 40mm.
For comparison - slightly larger Danae class cruisers had 5 6-inch guns, 1 twin 4-inch gun (AAA), 2 quad 40mm AAA and 8 twin 20mm AAA (some also 4 single 20mm).
But I'm not an expert on cruisers, so it would be good to have more opinions.