You seem to be confusing a few things, methyl.
The single currency has nothing at all to do with metrification. ("We should have finished the total Miles/Kilometers, Pound/Kilos and Pounds/Euros conversion in the 1970s.")
Leaving aside the fact that the euro was not launched until 1999, changing over to a different method of measuring weight and distance does not require any convergence of economies or fiscal policy. And the idea that travelling across the continent would be easier if only a single currency was in use was not the principle idea of the euro, it was simply a by-product. The money lost in those transactions (certainly that lost by individual travellers) is miniscule. As I'm sure you realise the main aim of the euro was to amalgamate the economies and fiscal policies of individual nation states to further enable centralisation and the progression of the "European Project" of full amalgamation into a single nation state.
To my eternal shame I too voted "yes" in the 1975 referendum. However it is quite clear now that, if the electorate was not misled then, things have changed so much that a new referendum is now needed. A glance at the government's pamphlet from that referendum will demonstrate why:
http://www.harvard-digital.co.uk/euro/pamphlet.htm#11
Among the salient points:
"No important new policy can be decided in Brussels or anywhere else without the consent of a British Minister answerable to a British Government and British Parliament."
Clearly no longer true.
"The Minister representing Britain can veto any proposal for a new law or a new tax if he considers it to be against British interests"
Clearly no longer true.
I wish you well if you decide to up sticks. You should bear in mind that if the UK does decide to depart, by the time it does so the euro will almost certainly no longer exist in its current form, the economies of the current eurozone nations (even some of the larger ones) will have declined considerably further by then, and you (and your money) will be resident in a moribund over-regulated declining bloc.