Bilbo, I expect you've done this but if not... make sure you're on the section for packages sent outside the UK, and that you've checked customer reference, not consignment number.
For people in the UK who are currently at Arnhem, TNT say the next stop is Northampton hub, where they expect my package today. Then the packages will be re-routed to the local depots (e.g. London for me). Still not promising I'll get it before the 30th though.