Astra van cuts out while driving then wont start till 30 min later and then only gets few more miles?

Astra van cuts out while driving then wont start till 30 min later and then only gets few more miles?
Sounds like the old classic "Ping Pong Ball in The Petrol Tank" trick, the car starts and you get a few clicks before the ball blocks up the fuel valve and the car stalls. takes a good 20 minutes for the bugger to float away and you can start the car again, for a few clicks, and you stall... rinse and repeat.