Thanks for the advice! I replaced both headlight units just in case with brand new ones. I'm wondering if maybe the fuse contacts were in fact corroded enough to keep the left headlight from working when i drove it home, and THAT might have heated the fuse block up a bit. Hopefully just cleaning the contacts and putting new fuses in will cure what ails. I'll have a go at that as time permits. I'm still de-rusting the rear hatch at the moment, so the car's off the road anyway.

Thanks!

Chris