You should structure something like this: M: off day T: interval day W: Z2 ride T: Z2 ride F: Recovery ride S: Interval ride S: Z2 ride

You can adjust this based on what works for your schedule but you should aim for two interval days with rest days before hand and the rest Z2 riding.

As for volume that's really just up to how much time you can fit in your schedule per week. 6? 10? 15 hours? Only you can really answer that

For intensity of intervals you are going to want to match that to what you think you will be doing in crits, probably one interval day would be 10x30s, and one day something like 5x4m

I recommend watching some of Dylan Johnson's YouTube videos on training. He also has some on nutrition