Due to work drivers dropping me off at 5am one too many times, I know the feeling (live a very long way from LHR, so drive time is 2-4 hours!). Been there for the shutters 3-4 times in last year.... and can confirm with the early slot they open 6:30-6:45 at times of year, so boarding commenced at 08:30 (this was back when Mumbai departed 09:30 hours in winter!). VS3 I believe now has same slot?
The private security channel also only opens at 06:30 - or did last time I was using it.
I wouldn't worry too much though - pre 7am there are not many in clubhouse, so you can get breakfast and spa appointments easily.
On the 340-600 would recommend the 10/11 on the left of the plane (when facing forward) - no-one opposite you and near first off, without the bar noise. Simples!