If you want a cheap flight from Norwich to Berlin, you've got zero airlines to choose from.
Berlin-tegel / Otto Lilienthal Airport is just one of the airports in Berlin. If you're not set on a specific airport, try changing your search from Berlin-tegel / Otto Lilienthal Airport to Berlin to see a broader range of flights – they might be cheaper.
If you're planning on going to Berlin during this time, you could take a look at other airport options. Or you could try to get a last-minute bargain.