Brexit is basically a country that was a superpower, that does not understand its place in the world. That's it, nothing more, nothing less. Because the UK is a small country and attained superpower status it has since lost that (1997) in an emerging globalist world of supernational organisations. (EU) I.e the world is getting smaller and smaller and were an average country, not a country leading in the global world. Brexit is an attempt to break out of that organisation in an attempt to regain that status. Post World War II from 1945 - 1965 was crucial, and not just the Suez crisis and French offer but in global and economic terms as well. That is India, Africa, Singapore, Hong Kong, UK industrial economy fell from by 80% from 1945-2010. It's been termed as the 'the long economic suicide'.
I disagree completely on your analysis on Brexit; in so far as vision of the country globally informed things, the forces powering Leave were basically anti-internationalist, retractionist, anti-globalisation, while Remain was internationalist and about power projecton. (Or as the Remain put it themselves, 'punching above our weight') It's not remotely as simplistic as Leave=Wants the Empire back. But anyway, this isn't a political discussion thread.
Decrying the decline of British status doesn't mean union with France was ever going to happen. You can polemicise about the issue of British power, it doesn't make Mollet, a unusually Anglophile French PM, batting around a vague and romantic scheme about merger a realistic proposition. You keep talking in terms which suggets you believe that it's as simple as Eden and Mollet verbally agreeing to Union, and then hey presto, it happens. This isn't how politics works, and it's certainly not how politics works in parliamentary systems.
Pre-Suez in particular, in Britain there was really almost no serious apetite amongst the political class as a whole for European integration - it would require Suez, years more of imperial fragmentation and ecnomic illusions falling away, and the rise of a wartime/inter-war political class which had a substantially different view of Europe to their predecessors, for the notion to even gain a minimal amount of traction in the possibility of EEC entry. (And even that was heavily contested)
So I'm puzzled, given you seem to also have a vague knowledge of the period, how you believe that pre-Suez Britain would have thought not just the intergovernmentalism of the EEC but
effectively merging the country would happen, and who would consent to this sceheme. And it would be no more easily accepted in France had Mollet brought the scheme home. If Eden and Mollet had started championing the concept, they might have had the priviledge of sharing the same exile in Ian Fleming's Goldeneye estate in Jamaica, but little else.
Even the diplomatic rapport of the Suez experience was never going to last, because it was based on a passing shared imperial angst. The French had as much if not more historical investment in the canal as Britain did, and like Britain they shared worries about the Nasser effect, in particular what it would cause in North Africa and Algeria. That was really it, it was a shared spasm of imperial decline on the part of the two foremost European imperial powers.
I think there are alternative routes Britain could have taken which would have seen it become a more integrated European force, even relatively late within the fifties, but this isn't it.