The Takeover Panel rules forbid another attempt within 12 months of a failed/withdrawn bid without approval. Which they would be unlikely to get, as the allowances for it are very specific. So "new bid in January" as claimed is realistically out - even if they got approval, it would take time to get it.
I'm pretty sure there's some Irish Stock Exchange rules on multiple failed bids but I can't find them now.
As Ryanair is an Irish company not UK then UK takeover panel rules are irrelevant and as EU looking at it then UK have no involvement.