Mother,
'The membership of the Euro is a difficult one, and probably with hindsight has not been good for the countries of southern Europe, but they have had significant problems of their own, for example not being able to collect tax and corruption, meaning their economies were not in great shape anyway..'
The above shows the inherent contradictions implicit in a single market without a single language, culture or tax system.
A lot of the world has similar problems to southern Europe but makes adjustments by continuously devaluing their FX and thus keeping their goods and services competitive. Granted, this is at a lower living standard than other countries but it does stabilise employment and GDP while (hopefully) other more meaningful improvements can be made.
On the other hand, aided and abetted by banks like Goldmans, it was somehow thought that entering the Euro at as strong an exchange rate as possible was good for southern Europe (as it meant peoples existing Lire/Peseta savings were worth more in Euro). These countries thus entered the Euro at the least competitive exchange rate possible and have been hobbled ever since. The Euro has been a mechanism to tax Southern Europe and recycle the profits to Germany (in the sales of underpriced cars and industrial goods).
Some will agree that the Euro is fatally flawed but want the European project to continue. Again this is not really possible. Having a single market with countries able to devalue their currencies at will (and use differential tax rates competitively) will merely allow a race to the bottom and fatally undermine Europe's competitiveness with the rest of the world. Europe's understandable reaction to the UK trying to 'have its cake and eat it' is no different to how the EC would work without the Euro; it wouldn't.
I am not sure whether dealing with the eventual inevitable collapse of the Euro (and EU as is) is better from without than within. There is no good choice. I was a reluctant remainer, based on the frictional costs of leaving, rather than a commitment to the idea of the EU (and I did not understand the half of it!). However, we are where we are, and we should try and get the best deal possible, considering the size, power and momentum of our economy. The idea of no trade deal is analogous to MAD. Yes, the EU have more economic nukes than we do, but we have enough to cause devastating damage, too. The US is reluctant to go militarily head-to-head with North Korea, which is far more of a mismatch than us going economically head-to-head with the EU. Clearly there is a chance of misjudged brinkmanship, but I am optimistic a reasonable compromise will be reached.