I've read a couple of times before that generally, the larger the number of individuals in the group, the less likely they are to be nippy. Don't know what level of truth there is in it though.
The two species you mentioned (neon + glowlight tetra) do better in 15+ US gallon tanks, so yours is a little small IMHO. What about microrasbora, ember tetras, pygmy cories or endlers instead?
Yes after doing some more reading up think i will stay away and add some small corys how many do you think i should add ive got the tank heavly planted as ive read that the bettas like this.
Sorry another question i have a hooded tank do i need to make sure the water level is a little lower than normal so that they can come to the surface.
Personal experience in my 20 gal I had 6 lowlight and 6I neon and they nipped my half moon to a jagged fin. Yes the more you have will help the nipping but the real problem lies within your tank size. The larger the tank the less they will meet and get curious. In my 20gal there just weren't enough room and they kept meeting and nipping.