Is BA the 'holy grail'? No.
Is it the best gig in the UK at the moment? Only person taking the leap can know. I am in BA, have been for 10 years. The first 18 months I wondered what I had done! After about 8 years I got used to it and sure enough, I now think it is great. (Bottom 20% of my current status)
Dont stress at what you can't change. Expect to be in the RHS for at least 10 years. Enjoy the lifestyle.
If you expect either a quick command, to be home every night, or to be anything other than a number, you will be disappointed. If on the other hand you are prepared to work hard and be happy to leave the complete mess that LHR is behind you when you leave the car park, then you will survive it.
One thing is for sure, this industry isn't what it used to be.