How to set fixed raid protection period.

I want to do a blanket offline raid protection for all bases on my server between a fixed time of 01:00 - 09:00 GMT every day for free, am I able to do this and if so how do I go about it?

That's unfortunately not a built-in feature of this plugin. It could be possible by manipulating permissions (granting raidprotection levels during that time and revoking them outside that time), but you'd need another plugin that does that.