You've probably seen the text on your TV about the 30th September upgrade to Freeview, but I suspect, after looking at the Freeview site, that there are going to be problems.
1. Channels might be moved to other numbers.
2. Some channels will no longer be available to some (ITV3 & ITV4).
3. Some Freeview boxes will no longer work :)
It might be a good idea to check if your Freeview box is one that wont work (see second link in next post)