Hi Huw,
Well done - doesn't sound a serious fail, and should get through on retest if you take note of the comments, which you obviously are.
For a source of all sorts of things lighting - high intensity headlamp bulbs (important once SVA is out of the way), LED brake, side and indicator lights etc, have a look at
Paul Goff's Lighting Site. He has everything you need, including P45t/P43t adapters to fit modern bulbs into our headlamp shells.
Geoff Gear's car passed SVA first time at Mitcham just before Christmas.
Tony