There are currently no plans to develop another terminal. There are, however, plans to develop a new pier and new stands.
The stands are currently being reviewed, and as I understand it will be created in blocks of 4 or 5 on the land between the existing remote stands and the fire station.
The new pier will more than likely be built where the fuel farm are currently, meaning the fuel farm will be moved probably to a site north of the fire station. This will probably not happen until 2006 at the earliest though, as the plans were only published in the Masterplan for 2006-2016 this year (as 10 DME ARC says) and planning applications etc will need to be submitted.
the airport has been heavily criticised for the current layout
I don't really see your point about the layout, after all, most people don't want to hang about at check-in, and for those that do, there are 2 cafés, one in either check-in hall, with WH Smiths, Greggs and the entrance to the departure lounge between the two.
The security area is no different to that which is found at other airports, a queueing system followed by the usual scanners, what more do you want?