I think that what you are feeling is perfectly natural. As humans, we fear being judged and looked down on. It is natural to wonder if you or your dog will measure up to the expectations of others. If you can try to relax and take it all in. Get to know the people and watch the interactions between the club members. See if it is a group of people that you will be able to gel with. IPO takes a lot of time so, don't think that it is only them who have to accept you, you also need to make sure these are people that you can work with.