I am flying Qantas J Syd to Heathrow .

I am flying Qantas J Syd to Heathrow . I have a 7 hour wait until connecting BA Clubworld to Toulouse . Can I hang out in a T3 lounge ( Emirates ? ) , or BA at T 5 . What is the best lounge ?

On arrival at T3 I have always been directed to an immediate transfer to T5. I assume there is no way of gaining entry to T3 lounges on arrival.

Why would you want to? The BA T3 lounges are average at best. Given T5 is the "BA terminal", BA have spent up big to make those lounges far superior to the ones in T3.

BA T5 has a better lounge. Use the South Lounge at T5.

Yes , you are probably right ..I have done this trip for several years , but this is the first time I have had such a long transit . Looks like it is a BA lounge at T5 for me . Next question ....which lounge is best ? ( north or south )

Agree with TRB: T5 South is best. I have had a similarly long wait for a TLS flight. Can at least catch the breakfast menu on arrival and the lunch menu before departing. 

Thanks for that , T 5 South is the go , so that is where I will be heading . Cheers .