Hydrated lime is the one to go for, slugs, leatherjackets and wireworms hate it.
If you use just gypsum, it will improve the soil texture but not change the pH, best to do a soil test to see what you need.
whichever you use , dont over do as you could do more harm than good.
You need to put lime on alone, 2/3 months after manure and 1 month after fertilizer.
If you have already manured, put lime on in February.