Hopefully I can give you a bit of perspective as a 'swim mum'. My teenage daughter swims to a very high standard and for the teacher to tell you your dd has Olympic potential aged 8 is frankly laughable.
She's got more chance of winning the lottery I'd say!
Swimming is a great sport for kids and my DD loves it, but no-one should ever join a swim club with the idea of becoming Olympic champion. Go into it instead because it is an amazing way of keeping fit, learning discipline, being confident, making friends for life and having so much fun.
There are incredible highs when you are a competitive swimmer but also crushing lows. Learning how to deal with the bad times (and there will be!) is as much an experience as when they are winning medals, qualifying for nationals or getting picked to represent their county.
It's a massive commitment - probably around 11 hours a week training once you are 12 or 13, whole weekends taken up with galas and meets and travelling around the country chasing qualifying times.
It's also a massive financial undertaking - on top of training fees you'll have to stump up gala fees (which can be £8 a race), petrol and travel costs, regular hotel bills, and equipment . Race suits cost £250 a time and you'll probably need two a year. Training costumes can be £40, goggles £30, hats a tenner.... I could go on and on.
Having said all that your daughter is 8. There's no reason for her to train more than twice a week right now. She can wear a cossie from Asda and a hat from Home Bargains.
As she progresses and gets older training will increase and you'll have to add mornings into the mix but that might not be until she's 10 or 11. She may never be good enough for that.
Don't get me wrong we have loved our life as swim parents of two children and when it comes to an end, which it will naturally when younger DD is about 18, I will be incredibly sad and probably wonder what to do with my life! We have had such good times and hopefully more to come. But even at the level dd is, she has literally no chance of becoming an Olympic swimmer. We know that, she knows that and so does her coach. To suggest anything else is fantasy land.
I hope your dd does join the swim club and loves it - it's so rewarding to have a talent and use it well - but please do go into it with your eyes open! Feel free to PM me if you want to know anymore.