travel bag advice for taking on a plane please!

[Nomtastic]

We are going on a long haul flight very soon and I need to buy a new bag to travel with on the plane. It needs to hold all the essentials to keep a 2 year old girl happy for 10 hours, plus essentials like passport, snacks and books etc.
Our buggy bag isn't really suitable as it doesn't close properly on the top.
Has anyone bought one recently for under £100?

Shouldn't need to be an expensive one -we have used a kids rucksack before from Disney shop or sansomite kids luggage type rucksack.
If they have a few different zip pockets then I usually put a change of clothes in one pocket , snacks in another and toys , comforter , crayons etc in the main one.
I normally keep passport , nappy changing stuff and beaker etc in with my hand luggage.

Kipling Becky