My turn to be a little absent now. I'm going through a break up, so being a bit shit right now. But I shall begin on a post after I have finished my other post for another role play.
As you have Katie as quite the rough player, perhaps throw in some of the countries that England really hate? When it comes to sports, we hate any of the other UK teams, Germany and Argentina etc. So that'd give lots of opportunities for her to misbehave on field.
Germany, Argentina, Scotland, Wales, Ireland. Then maybe 4 non European teams too?
Either is fine, but if Quidditch seasons are based on the Premier league (which I think it is) the premier league ends in May, and then the World cup starts in June and plays over 4/5 weeks. So maybe we could do it from the end of the Quidditch season, when all focus is on the World Cup.