Rather than asking here for tapping size drills for each size, just google for "tapping size for metric threads" - there are plenty of tables of sizes around that will give you everything you need. The only thing to watch is that there are various pitches for each nominal diameter - hence metric coarse, metric fine, etc. Generally you find metric coarse (if you just ask for M4, M6, etc, that's what you will generally get), but you should be able to read the pitch off the tap to double-check.

I'm not saying that you shouldn't ask questions - just that there are easier ways to find some information for when you want the answer NOW and not when someone gets round to answering!