Does anybody else have a problem where there lights dip when not on the accelerator, for instance when in reverse the rear reverse lights nearly go out when i take my foot off, same with the interior fan and lights?

drive a 1.4 8v by any chance?

If so, join the club

My old Ibiza PD130 Sport did this, and being as that and the Fabia are rather closely related I would guess this is just 'one of those things', not noticed if my Fabia does it yet as I've not driven it in the dark yet!

Yep - noticed that by vRS does it a few weeks back.

Same here - doesn't do it very often though, that said I don't like it much as with a new battery etc this shouldn't happen IMHO

The power steering is electrically driven I belive and this causes the flickering as it does it on our 1.9pd,its noticeable when going in reverse !

It's the electrical system going under load and back to normal again - most cars (with exception of expensive ones) do it to one degree or another.