HELP, Kind People.

I have an already converted loft but they have blocked off a quarter of the roof for in the eves for storage. I'm wanting to knock this out and make it one big room. The problem i have is i'm unsure what to do about the floor. In a perfect world i want to but two ledger boards either side and run 2-3 beams across using joist hangers. But the span across is around 5M. This would be neigh on impossible to get three 5M lengths of timber into the attic. Does anyone have any suggestions? Is it possible to get two 3M lengths and sister them together, or is this daft? Please help guys.