Ooh, we have this cock ring - both love it, works well for him and by far the best in our toy box for me so good choice! Usually pop it on before he’s fully hard, doesn’t stop him getting hard but makes getting it on much, much easier.
In terms of waterbased lubes, there was this thread fairly recently which you might find useful:
Lube recommendations for sensitive skin
Sliquid lubes get a lot of love from those with sensitive skin so Sliquid H2O might be a good choice? Also, it’s just a very good lube. Lovehoney also do the Sliquid organics range but are currently out of stock.