Churchill's government in the early 1950s was Euroskeptic (or at least Euroschizophrenic) to a ridiculous level. They were torn between Europe, the USA and the Commonwealth and made a pig's breakfast of talks on the EEC.
The Belgians led the call for British membership of the proto-EU in the 1950s and were rewarded for their efforts by two-faced diplomacy as Eden at the Foreign Office officially agreed while attempting to scare off the smaller countries, which rightfully angered the French and others. Basically the UK's initial policy was to try and sink the whole idea simply so they didn't have to decide and could maintain strong (and even by then, obviously dying) trade links with the Commonwealth.
By the time Macmillan became PM Britain's standing in the European 'brotherhood of nations' was extremly low and the fact France was cut out of Anglo-American nuclear dealings didnt help the UK's case. De Gaulle gets blamed for it but Britain was all over the place and certainly didn't look like a commited entrant to the EEC.
Say Labour's 1951 sucess in popular votes translates into seats and they stay in power, the EU could turn into a very different organisaton. One of the big worries for Churchill and Eden was that the French Foreign Minister Schuman who eventually set up the Steel & Coal Community mentioned the idea of a integrated European military. If Attlee stays in power, Britain might be keen on the idea to an extent, as Labour's hawkish military policy was aimed at setting up large conventional forces on the continent to counter the Red Army. Say Britain pushes for an intergrated high command system for the Europeans, possibly under auspices of NATO.
At least you might see a more level headed response to the EEC, and if Britain is pushing for military cooperation, they may be interested in including France in nuclear talks. All in all, DeGaulle might be a lot more friendly to British entrance.