Given that CCBC are discussing a potential £400K spending on alterations, I hope they take the opportunity to take a step back, and reconsider the place's function. I don't see how it's going to be financially "sustainable", even if a bistro or cafe does get set up. The figures published show the problem.
It's a large building. Much of the space is poorly utilised (or not utilised at all). Although there's probably not much that can be done about the oversized toilet-and-corridor block (which takes up the whole zinc skip section), they could reconsider the ample space that's currently set aside for conference rooms, and the central section with the pointless big round reception desk, and the space around it that seems wasted.
It needs some imagination. What kind of fun things do people want at a seaside? Look at all the seaside stuff on, say, Llandudno pier. Now imagine Llandudno pier with conference rooms and giant windowless block of corridors and changing roooms replacing the end arcade section.
Currently Porth Eirias has all the "ambience" of a council meeting room. (And that's probably because most of the design input came from people who spend most of their time in council meeting rooms!).