You may see flotillas of literally hundreds of these on reservoirs and gravel pits around the south east of England during winter, but you'll not see them fly that often.
The goosander is our largest sawbill, (Grebes / Divers etc...) and because of its fine abiliy to catch fish, it has been persecuted widely by some angling groups. I think it still has no protected status in Scotland for example, where it is spreading, and a few nest.
We only saw one Drake Goosander on our New Forest break, flying hard and fast for one of the lagoons.
Nice to see though.