The word "extension" is a little misleading. Technically yes, a pier is an extension, but don't imagine this as an extension to a terminal which resembles a shopping mall with check in, central search etc. This is downstream of that.
I'd have thought £14m will buy a decent pier with 5 gates. If the pier is to feed the stands which already exist to the east of the terminal, rather than having to build new ones, then you might even get some toilets, newsagent and coffee bar too
