Thank you for your help everyone. I have decided against booking with eDreams. I imagine that the old rule 'if its too good to be true it probably isn't' applies here and I have heard some horror stories about eDreams on forums.

Decided to move dates forward a day and I can now book the flights with BA directly for £444. This is the first long haul flight I've booked, but I have had a good look around on price comparison sites and this seems like a good deal to me, unless anyone can suggest any cheaper alternatives?

Thanks