Following a bad graphics driver update leaving my screen completely black at boot I had a huge amount of trouble getting into Safe Mode to roll back the driver.
First off the problem is that F8 doesn't work any more to get into the Boot Options screen at startup. Sources on the internet suggest Shift+F8 but this doesn't appear to work for Sony Vaios.
If you do manage to get to the W8 Recovery screen, going to
Troubleshoot > Advanced Options as suggested by How to Geek doesn't have the Windows Startup Options option.
I post my answer below to save anyone else who has this problem a few hours of headache.