You could just get the KIT, and assemble it while still flying your trainer. If you are ready to move on from your trainer but are still not ready for the UCD, then get something in between while finishing the UCD kit. If you are ready for the UCD, then at least the fact you have to build it from a kit will prevent you from jumping into it too soon as youll need the time to assemble it.

I only say this because it sounds like youre hooked, so getting a plane that may not be used till youre ready for that 3rd plane isnt much of an issue, it sounds like youll stay with the hobby and get to that point anyway.