Try these usernames.
jaleel
mcq
(Or type in 'ugleis' in the title box)
They have some awesome 3rd rain that you should try. Scroll down if you don't see it.
Err, the third rail he is after, is the top contact type (As the following image demostrates at my local station:
http://russellsphotos.fotopic.net/p39270836.html
).
I think the types you are referring to, are top/side/underside contact, none which are entirely appropiate for British Rail Southern Region modelling.
Edit: This is a good advert for Mike10s 3rd rail stuff:
Funny enough, the station I modelled is Fishbourne!
Another advert is this junction, although, I have another complicated junction that shows more gaps in the rails than this shot, it was at the other end of the station (which I remodelled).
The control of the rails, is soo great, they look good with any track type, well almost!
I however, do agree that they are difficult to control. For authenicity and matching, its best to lower the con rail by 8cm or raise the trackbed by 8cm.
EDIT: Yes, I know, I broke the CoC on this one, I CBB to resize them to 640x480.