I applied for four "Follow my team" tickets. I think the draw for tickets takes place at the end of January. If I get the tickets I will go. To answer your question I think after this draw people who dont need all of their tickets UEFA will have a marketplace on their website to trade and exchange tickets for the actual face value. I expect that for group games were smaller teams are involved there should not be any problem to get tickets at all.
Hire a native UK gambling writer now - Contact me via PM or Email: floohub@gmail.com