Crampons are fixtures designed to attach onto your shoes as you walk or climb, and they are built specifically for use over snow and ice. Crampons prevent damage to either your feet or you walking boots, and also provide you with better traction on slippery surfaces.
Crampons come in varied amounts of rigidity and flexibility. If you wear crampons with the wrong rigidity of shoes, such as shoes that are not technical, or too flexible, your crampon will simply fall apart.
If not, and your set on buying crampons later if you need them, then the boot you need is a B2. This has the most flexibility in that a B2 rated boot ensures you can walk with both a C1 and a C2 crampon, allowing you to experiment with your climbing style, before considering moving up to a B3 boot later on.
C1 refers to a flexible style of crampon that is able to fit a B1 Rated Boot.
C3 refers to a very rigid style of crampon that is able to fit a B3 Rated Boot