There is a great waterproof 40spf sunscreen out there by Coppertone. My DH uses it and plans on it in November when we go. He is extremely fair skinned and burns just thinking about going in the sun.
Also we are getting him a rash gaurd and I would suggest you get that also. You can wear it over your suit and then just put suncreen on your arms. They do make rash guards in long sleeve also though.
Just google Rash Guards and you will get a ton of sites that come up. They range anywhere in the $20-$40 range. Definitely worth the money.