I doubt most will do externships this year. But here's my 2 cents:
I would say honestly don't worry too much about not knowing much - as long as you are aware and open about it people *should* be nice and help you out. They usually want to help you learn and probably don't expect you to actually know anything.
I would focus more on externing where you might want to go, especially because some can be expensive to visit (plane/car, hotel at some, food, ect). A lot of people go to their home program first and I'd hope they would know a bit about what you've learned so far so it shouldn't be too bad.
To actually answer the question: I think UW is hands off unless you go there already!