I reckon you'd be looking at a pretty light outfit for a 6 yo. That is all you need to target bream, whiting and flathead anyway. I would suggest something around 6' in length with a spinning reel or maybe an alvey 500B. 8-12 lb line would suit. I am sure there would be dozens of combos like this in the large chain stores pretty cheap.
Can't help you with any specific spots, but there are a few flathead moving around. The mouth of a drain off the flats at the start of the run out would be a good choice.
Jeremy