ERM and the Euro, whilst somewhat entwined are not mutually inclusive. The reason the UK never took on the Euro, was many fold and nothing to do with Mr Soros and the great EMF gamification for printing money.
If they did a referendum upon the Pound and the Euro in the UK, the result would be much clearer and conclusive than any membership referendum. Heck, even Scotland if it leaves the UK, wants to keep the Pound.
AS for the Euro, it worries me, so much QE has been actioned by the ECB, that it just feels like, once that eventually stops https://www.reuters.com/article/us-eurozone-ecb-qe/the-life-... though they have instigated new QE measures this year.
One aspect the UK has impacted the Euro has been in blocking (as a members vote) many initiatives to control the financial markets and with that, been instrumental in curtailing the controls needed for a large encompassing currency.
But I totally disagree that the UK's primary reason for adopting the Euro was due to the ERM shenanigans. https://www.economicshelp.org/blog/215/uncategorized/why-uk-... covers some reasons. But to say it is complicated is part and parcel of any currency control.
Remember, the UK's key income area's are Financial and Services, two area's in which the EU has been stymied to take control of, mostly due to it not being in the UK's main interest. Heck, even opening up services has been a backfoot EU initiative with members still not opening up those markets. But that is another matter, equally complicated and hard to summarize in a few sentences.