Thanks for the replies, I know this sort of work is not for everyone.
I guess I have been switched on to the company by the advertisements that specify the opportunity to fly a 747 with modest experience requirements. I have spent many years flying smaller aeroplanes in some really challenging environments, and I must stress using multi crew SOP's derived from big aeroplane Operations Manuals. I have been fortunate to fly for smaller but correctly run companies.
I grew up looking at Aer Lingus 707 and 747's climbing out of Dublins old runway 24. Hoped one day I would fly one.
Keep the replies coming, interested to hear all your views.