If it's anything like Mondeo units the lens is glued to the plastic surround. There are some clips that you prise off, then with a big screwdriver carefully lever the two halves apart. With a very sharp blade cut the adhesive as you go and you can gradually pull them apart.

It's easier if the units are warm (leave them over a radiator for an hour or so) as it softens the glue.

Even if you do clean them, and fit groovy bulbs the light is never going to be amazing as they're a bit of a shit design, and even from new they were rubbish headlights.

Cochyn - How badly scuffed were your lights? One of mine (that I got from a breaker) has obviously been stored face down, and is noticeable scuffed. I assumed Autosol, or similar would just make them even more scuffed?