Hope it all goes well for you both ksst! ...keep up the open and honest communication both ways!
His reticence for engaging in breath play may stem from simple inexperience with whats safe or not with it or could even come from a fear on his part as well, like a fear of hurting you, or loosing control etc and inadvertently bringing harm.
Outside of online and written resources a good place to find someone who has real life experience with this kind of play would be a fetish convention, a public access club/dungeon or local community group/munch venue.
http://tribes.tribe.net/bdsmtipstech...b-2b2fa4fe5978 is a good place to see some of the pros and cons discussed by others and find extra resources.
I personally like a little breath play, not just choking (shivers at the thought of a pair of strong hands wrapping around my throat...obviously my fav form of it) but also the kind involving rope harnesses and corsets.
It can imho be safely delved into and enjoyed if one is careful and knowledgeable of the dangers etc.