I’d like to get at the front sprocket to remove the gunk that has accumulated around it and the chain, but I’m a bit concerned what would happen when I take off this plastic cover. I suspect that there’s a metal plate under it and the innards won’t spill out onto the road, but I need a little bit of reassurance, because I’m a snowflake. All advice welcome. 
 

 

Beyond possibly finding signs of water ingress at the flywheel you'll be ok.

Yep - nothing will fall out (unless there has been a massive disaster, but then I guess you'd know about it beforehand!!). Careful not to over tighten the screws when you put it back on as it can distort a bit - there are metal inserts in the plastic, but even so...

also - def not a "snowflake" if you are doing the maintenance yourself!!

Lot of people cut the sprocket guard off the ignition cover as it used to clog up with mud,better off without it

Thanks, everyone. I'll take it off tomorrow and get everything cleaned properly. It long overdue a cleaning.