While I have not checked specifically, food in Europe is around 10% more expensive than in the UK anyway so in terms of supplies a similar increase, possibly caused by the fall in value of the pound, is not unreasonable. It is not a 'war' scenario in the slightest it just needs organising. The EU has said all along that it is wanting to negotiate 'new deals' but it is the UK government that are playing silly buggers and so far seem to have gone all out to be as unreasonable as possible. You have to remember it is the UK that is leaving. The 'rules' are well documented but rather than looking at the rules, many of which the UK will have been involved in writing, they set a bunch of 'red lines' that were always impossible to make the EU accept for very good reasons. If you are a member of a tennis club and you turn up with a cricket bat, it is unreasonable to expect the club to change. The bottom line isn't much more complicated than this. If the UK is thinking of using blackmail to get concessions it might well come unstuck. Remember the UK has to trade with somebody as it cannot feed itself and the whole world has been watching this weird game with incredulity.