I hadn't really thought about tsunamis hitting the UK till fairly recently , but it seems they are more likely than I had thought.
So many disasters could hit us , but I think it is man that is more likely to cause problems that we may face . Although things like solar flares knocking out electricity stations etc and other essential technology that we depend on , could hit us very hard and very fast .
I think you need stuff that would get you through the first few weeks of a disaster , kept safely where you can get it easily if need be.
You need to think of water first .... water from the tap may be one of the first things to stop . So a way of filtering water is essential . You can buy all sorts of expensive crap , but good old sand and gravel will do the job almost for free , time being the only real cost. Once filtered, any rain water , or as clean as possible source , can be used to wash clothes if need be , as is . But if you want to drink it , it has to be boiled first .
So next on the list is fuel for cooking/boiling water . That will be whatever you have around you . Gas in bottles , or wood or coal , dependent on where you are .
A good basic first aid kit , plasters , bandages ,germolene , detol , aspirin ,paracetamol ,ibubrofen ( tabs + gel) + a needle and thread ( a curved needle works best !!) . If you are blind like me , a spare pair of specs would be handy .
Next would be whatever type of food you eat that will last a few weeks , so dried or tinned .
The above would be for emergency get you by type things , if you were at home . If you were outside , the list grows ... you need a tent , one that can be carried easily . Sleeping bag , camping cookware and eating utensils . Good outdoor clothing and waterproofs , and good walking boots.
The list can go on as long as you want it too really . But if you are on the move , you have to be able to carry it all in a rucksack , so keep the weight to a max of 80lbs for a man and about 50 or 60lb for a woman . Sorry ladies , not being sexist there , just that most men can manage a bit more weight than the girls can .
It is hard for me to think of all the things needed in such a situation , as I have everything I need already really . But that only applies if I am on the land where I am set up . If I was on the move , I would go as light as poss . Just the clothes I stand up in , a knife , and sort out from there.
Shelter , for example , would be a plastic bag and squeeze under a hedge somewhere . Food whatever I could find or catch . It all depends on circumstances really . But whatever comes along .... I won't give in without a bloody good go at surviving , all assuming I don't pop me clogs in me sleep tonight !!!!

cheers
Russ