I do not worry about extreme long term shelf life. The containers the food is packed in will not last the extent of the projected shelf life.
I don't have 35 years left, why should I store for a 35 year incident?
Doubt I would last 15 months in a true SHTF situation due to lack of meds.
I have a year supply set aside and rotate it out. I eat out of my supply pantry daily and restock weekly.
No powdered eggs for me thank you, I have chickens in the back yard.
Coffee and tea is my big downfall. Every time I go to resupply it has gone up in price, and not by just a little.
Fortunately I have resupply on my tea comming from you folks. We can not get decent tea over here and one of my Brit friends sends me a supply every now and then.
WAAAAAAY better than what we have!
This is going to rub you anti-religious folk the wrong way, but the Church of Latter Day Saints runs an excellent food storage program that is open to the public. I understand they are a strong group in Great Britian and I am sure they run the same programs over there.
Their church has undergone so much perscution that they require their members to be self sufficient for 1 year.
Not promoting their religion, only the services they provide
http://www.providentliving.org/self-reliance?lang=eng
Due to thuis being a religious group they probably avoid some of the duties and import charges.
They also do canning and on the location food storage.