Hi all,
I'm flying from Cape Town to Edinburgh on BA next month, and I just realised that I have a 6 hour layover in Heathrow T5

Totally my fault, I didn't notice when I booked.
I'm on the cheapest ticket, no status - is it worth trying to get on an earlier flight when I land at Heathrow? Or is that just something that can't be done on a non-refundable ticket?
Alternatively, are there any pay lounges in T5 where I can hang out for a while? It's a long time to sit around doing nothing after an 11 or 12 hour flight!