Welcome

finepics, gearing is a personal thing, but riding anywhere between 65" and 70 GI, gear inches, is generally the norm for town riding, and its usually best to gear down from what you find comfortable freewheel or geared to fixed, 46x16 works out to be 77" so 46x18 69 GI or 46x19 65 GI would be better for you and your knees, if you went fixed.
But only you would know what would be best for you...

Thats very interesting. Got to start learning all this terminology. I only ended up with a 46 chainring cos the bike came with an unrideable 39, so last monday bank hol the only ring I could get was 46 - I already really like this ratio so wondering how the 18 rear would translate in laymans (noob) terms!!

As for biting - I make teeth for a living - make of that what you will!!