The cornerstone of any professional pilot’s training is a solid training course for learning how to fly by the instruments, i.e. without visibility outside the cockpit. The Instrument Rating (IR) gives you the right to “file IFR” (to fly by the Instrument Flight Rules) and enter clouds on the way, and it will make your pre-flight route planning much more straightforward. You have all the interest in making sure you get the best training for obtaining the Instrument Rating (IR), even if you were to use it only as a private pilot. It can be accomplished either all in a single-engine aircraft or as a combination of single- and multi-engine aircraft. The extent of the practical flying part is at minimum 50 flight hours.
By the way, did you know that nowadays colour blindness is not an obstacle for obtaining the Instrument Rating (IR)? It may still prevent you from flying at night, but even without the Night Flying rating/endorsement, you can fly under IFR during day. If you hold a Class 2 medical certificate, do ensure you become “IFR checked”, which normally only entails a hearing test (the audiogramme) — no vision testing. There are no prerequisites as regards experience or prior training received apart from holding a PPL (or CPL) licence.