Global_Global ...
Far too pessimistic. There is one key factor to bear in mind in all this: the EU bloc exports more to the UK than we export to them. The trade balance is very much in their favour. Given that the UK is displaying little or no inclination to introduce tariff barriers or initiate a trade war, why should we suppose that the EU bloc would themselves act to jeopardise their already favourable position? Apart from which, the UK public appear favourably disposed towards the Single European Market (including many pro-BREXIT folks) ... other issues / concerns are driving the debate.
I expect a continuing torrent of scaremongering as referendum day approaches, but little change in trading agreements thereafter. Our based carriers can relax and chill!