So yeah I've got one of these coming up next week. What is the etiquette for this?

Presumably I'll still have to dress up. But I'll feel silly dressing up to sit in my bedroom. I could do the classic newsreader trick of not wearing any trousers under the desk. But yeah really, how does this work? I'll need to tidy my room as well won't I? Also my internet is really shit. If it goes down or is lagging will I automatically FAIL?