Holiday to Eastern Australia

My husband & I have a wedding in Australia March 2027. We'll be flying from the UK with a 4 year old and a 6 month old baby.

We've never been to Australia before and I go through phases of being excited to being anxious with the idea of going with 2 small children and the expense.

If we do go, we'll be looking at going for 3 weeks and trying to make the most of our time there while also not overdoing it with our children. As much as we want to cram things in i want to make sure we're all enjoying!

We were thinking of spending 4-5 days in Sydney before heading to hunters valley for the wedding. Then hiring a campervan for 7-10 days to head towards Byron bay with stops in between. I've mentioned this to a friend in work who was quite shocked with us only going as far as Byron bay but I'm cautious with over doing it travel wise with the children? Then travelling back to Sydney (flight or driving, unsure as of yet) to end the holiday in Jervis bay for 4-6 days before flying home.

I was hoping to get advice from anyone whether this trip is a good idea or not basically 🙈 Any recommendations on route/stops would be much appreciated!