Here are the points that Elwyn mentioned, followed by those that he did not mention:
 Seminars can be challenging if you are unfamiliar with this method of teaching.
 Students are expected to take part by speaking in seminars.
 Seminar discussion may focus on a piece of reading or research.
 In seminars, the tutor guides the discussion and encourages the students to take part.
 Learning through an exchange of views is central to most seminars.
 Students should be willing to speak and listen to each others' opinions in seminars.

 Some students express their ideas spontaneously. (Elwyn says that sometimes students feel that they can't express complex ideas spontaneously)
 It's not necessary to prepare in advance for seminars. (Elwyn says that it is important for students to come prepared to a seminar)

The seminar is probably the most common method of teaching in use at university in the UK, so if you have not experienced seminars in your home country, it is useful to know in advance what you can expect. As Elwyn says, this style of learning can be a challenge for international students at first, and it may take a little time for you to feel comfortable about participating in seminar discussion. Even if you feel shy about the prospect of taking part in seminars, once you have made your first contribution to the discussion, you should start to feel more comfortable and enjoy this way of learning.