It really depends on which type of situation you think might happen. What you have is a good starting point for a home survival kit. If you think we
are on the brink of something catastrophic their are many threads discussing everything you could ever need.
I take a view that localised desasters are far more probable than (for instance) a metior strike, so i plan accordingly.
Presuming you are planning for electrical outages caused my a major storm which means no shops open etc.
Food, you could make your desaster a little better by having more than tinned tuna. Think about buying a small camping stove that you can heat up
other sorts of tinned food. Chocolate, dried fruit and jerky also have the ability to be stored for long periods of time. How much to stockpile
depends on how long you think your family would be without help. 2 weeks food per person would probably see out any storm. Their is always what is in
the cupboards aswell.
Water,quite a nice thread
Herethat explains all about storing water. I just buy packs
of 6x2Litre water but i use it all the time for work so i change it out as i use it. That thread tells you alot about storing water tho.
As far as clothing and blankets go, you probably have the right clothes for the conditions, but i would see if you can get a portable propane heater
which would heat up a room and lift morale.