Sue, I don't think it is possible to search on that website without a surname, what I try to do is find one on freebmd and then look on the iow website that you mention. I then look for a marriage either on the same site or freebmd. Is this what you mean. Sorry I am a bit confused of how you search alphabetically on the iow site.
I am meanwhile sifting through the information that you found which I thank you big time, and having another look at the iow site to see if there is anything I have missed in relation to what you say.
Ewan