There are number of components that make up the requirements that would satisfy an airfield being CAT 2or3
1. The aircraft itself must be capable of performing a cat 3 approach(usually with autoland)this requires a visibilty down the runway of 200m(cat3A), 150m(cat3B), or lower which would be cat3C, they all need a height above the runway of around 50FT at which the pilots must be able to see at least some component of the runway lighting system in order to make the decision to allow the aircraft go land itself.
2.Both pilots on board must be trained in the simulator in cat2 or cat3 approach operations and both must have practised doing them in good weather in the recent past(usually one a month)
3. The airport itself must have an Instrument Landing system (ILS) that is capable of allowing an aircraft to make an automatic landing. The runway must also be of certain size and have adequate lighting systems.
4. The terrain surrounding the airport, particularly the part under the final approach has to be pretty uniform in height as the landing systems rely heavilly on Radio Altimeter information which measures height above the ground by bouncing radio waves off the land beneath the aircraft.
Finally you do not say which airline you flew with, but if it was a (fully servicable, British Airways RJ100 it would be cat3. If it was a British European 146 I think they are only cat2)
Unfortunately all that said Jersey is only a Category ONE airfield so no matter how fancy the aircraft, the pilots still need a runway visibillity of around 550metres and they must be able to see the ground by 200ft above the airfield.If this is not the case then I am afraid you end up doing exactly what you did much to the annoyance of your company and lots of fare paying passengers who can usually see all the island except the bit thar you are trying to land on!!
Hope this helps, I would be pleased to answer any bits I have missed out.
[ 26 August 2001: Message edited by: spoilers yellow ]