While I'm not a clearance diver, I'm the diving medicine PA that directly supports one of the FDU's. Your QL5 course is roughly a year long, if you make it through the 10 day prelim. The next year or so will be spent consolidating what you've learned, getting more advanced EOD courses, doing diving jobs to support current Fleet ops, could end up training Ship's Team Diver courses, etc. They have been deploying abroad on multinational exercises and live deployments in support of land or maritime EOD and Fleet diving ops. Once you're EOD trained, you'll eventually become involved in dealing with maritime and land EOD as a regional task wherever you're posted. There are also exchange/secondment positions with the RN and RNZN. You'll also be responsible to help operate the recompression chambers where you're posted, as well as inpsect and maintain diving equipment, both your own unit's and those of other Fleet assets. You also can go on TD to the Experimental Dive Unit in Toronto to participate in diving research as a lab rat. I suppose one of the worst comments I hear from folks here is that once they're done their 5's, they aren't diving as frequently as they'd like, which is something that's being very closely looked at.
Hope that helps.