OP here, I think I may have dodged a bullet!
To be fair, Cain gave me spot-on advice and as I read the posts here I was intrigued to see that people were still discussing bulb changing.
It seems that with the recent changes to MOT rules, your only options are to keep your halogen headlights or fit sealed unit LEDs. Have I got that correct?
Whilst researching this subject I discovered that headlight optics are specifically designed for the characteristic of the intended bulbs only. Every different bulb type has specific characteristics and wrong optics for the bulb is the cause of glare and unfocussed light pooling. This can obviously be a danger to others, so it is no surprise the rules have changed accordingly.
Of course we've all got away with stuff at the MOT centre, but it is always a risk and this has been getting publicity recently, so testers may be more aware - I don't know.
