ust incase anyone else has the same question here is a bit more info I have gleaned.
1) Instructor Rating requires CPL
2) CPL requires either Night VFR or Command Rating
3) Currently colour vision restriction precludes Night VFR
4) Command Rating comes in two parts (I think) day IMC and night IMC
Not quite correct. There is no requirement to hold a NVFR or instrument rating to hold a CPL. However (there's always a 'however'), if you can't pass a colour vision test your licence may (or will) be limited to 'Day only' so even future night or instrument training won't give night privileges.
An instructor rating requires NVFR privileges. This can be achieved by holding either a NVFR endorsement *or* a Command Instrument Rating + the addtional experience that then allows a CIR holder to use NVFR procedures. A 'bare' CIR isn't enough.
A CIR doesn't come in two parts. A CIR is a CIR. Once you have the rating you can use IFR procedures by day or night. If your licence has a Day Only restriction you might be able to get an IR that is limited to day only too.
Similarly with the instructor rating: You might be able to obtain an instructor rating without the NVFR requirement and have it limited to Day Only.