I know this is a bit late but I only just saw this! You see I only joined to answer this as I'm not a Mum, I'm actually a very happy IGGY member! If you are still unsure about joining, you really should. It had improved my confidence and made me so much more interested in certain topics. It has given me a place for intellectual debate, and a support system about university application and academic help etc. No regrets, you should definitely join.
My DD school have suggested she might like to join IGGY. They will pay her membership. We have looked at the website but still can't decide if she would really gain anything from joining. Also she is concerned about how much extra work she would be expected to do. We are going to chat to school tomorrow to see what they expect her to gain from her membership but wondered if anyone has any personal experience of the site. Thanks