Hopefully in throwing your own Biggest Morning Tea ways to fund raise should be at the forefront of your mind, there are many different ways you can get your guests to contribute and this is but one of my own suggestions.
Why not set up a simple 'photo-booth' for your guests to have their picture taken with prints able to be purchased and funds donated to the worthy cause of cancer research and prevention (you can find the details here). This is a different and fun way and relatively low-cost meaning more will make it to the Cancer Council!
here is pretty comprehensive and easy to follow.
If you want to keep it super simple and fun just go for a plain backdrop and use props to make it fun. Jordan from Oh Happy Day regularly offers free printable photo booth props like this one or you could easily collect materials and come up with your own. Ideas are endless but if you want some inspiration I suggest heading over to Smilebooth - they have the absolute best and funnest looking photo booths in the business
Good luck and happy fundraising!! :)