Bomma - I'll get back to you. 
Lau - I'm doing the Ace Toy Run next sunday (take it you mean 21st?) so wouldn't be able to get there (working this sun too). Hadn't thought of jumbles though - do you see many complete bikes at these? Ones that actually run/worth buying?
No as in this coming weekend 12th?
It's pot luck, some months theres stacks of them, other months you might find it to be mainly spares, but a lot of the people that go are traders, and go every month.
Newark is the biggest in the country, some months theres over 3000 stalls.
You do get a lot of shit heaps, theres no doubt about it, but theres also a fair few good bikes there aswell, runners, t+t, ride away jobs.