Hate to disappoint you Allan C but:

Only the Government of the United Kingdom has the power to call and hold referenda, whether they affect the UK as a whole or its constituent parts.

Since 1973 there have been twelve referendums held by the Government of the United Kingdom, the majority of them have been related to the issue of devolution. The first UK-wide referendum was held in 1975 on the United Kingdom's continued membership of the European Community.

1: Northern Ireland sovereignty referendum, 1973, on whether Northern Ireland should remain part of the United Kingdom or join the Republic of Ireland - Result remain part of the UK

2: United Kingdom European Communities membership referendum, 1975, on whether the UK should remain part of the European Economic Community - Result remain part of the EEC

3: Scottish devolution referendum, 1979, on whether there should be a Scottish Assembly - Result a small majority voted yes, but fell short of the 40% threshold required to enact devolution

4: Welsh devolution referendum, 1979, on whether there should be a Welsh Assembly - Result no

5: Scottish devolution referendum, 1997, Two questions: On whether there should be a Scottish Parliament - Result yes; On whether a Scottish Parliament should have tax varying powers - Result yes

6: Welsh devolution referendum, 1997, on whether there should be a National Assembly for Wales - Result yes

7: Greater London Authority referendum, 1998, on whether there should be a Mayor of London and Greater London Authority - Result yes

8: Northern Ireland Belfast Agreement referendum, 1998, on the Good Friday Agreement - Result yes

9: North East England devolution referendum, 2004, on an elected regional assembly - Result no

10: Welsh devolution referendum, 2011 - Result yes

11: United Kingdom Alternative Vote referendum, 2011, 5 May 2011 - Result no

12: Scottish independence referendum, 2014 on the question "Should Scotland be an independent country?", 18 September 2014 - Result NO

Looking at the above although there have been 12 referenda held since 1973 only two of them have involved the electorate of the whole of the UK. As it is the UK that is the EU Member state then any proposed referendum that seeks to alter the status of the United Kingdom's EU Membership will be exactly the same as the one held in 1975 and it would involve a voting process involving the electorate of the whole of the UK.

No precedent was set with regard to the Scottish Independence Referendum, strictly limited temporary powers were transferred as can be seen from reading the following:

Legality of a referendum:
There was debate as to whether the Scottish Parliament had the power to legislate for a referendum relating to the issue of Scottish independence, as the constitution is a reserved matter for the UK Parliament. The Scottish government insisted in 2010 that they could legislate for a referendum, as it would be an "advisory referendum on extending the powers of the Scottish Parliament", whose result would "have no legal effect on the Union". Lord Wallace, Advocate General for Scotland, said in January 2012 that holding a referendum concerning the constitution would be outside the legislative power of the Scottish Parliament and that private individuals could challenge a Scottish Parliament referendum bill.

The two governments signed the Edinburgh Agreement, which allowed for the temporary transfer of legal authority. In accordance with the Edinburgh Agreement, the UK government drafted an Order in Council granting the Scottish Parliament the necessary powers to hold, on or before 31 December 2014, an independence referendum. The draft Order was approved by resolutions of both Houses of Parliament, and the Order, titled The Scotland Act 1998 (Modification of Schedule 5) Order 2013, was approved by The Queen, following the advice of Her Ministers, at a meeting of the Privy Council on 12 February 2013. Under the powers temporarily transferred from Westminster under the section 30 Order, the Scottish Parliament adopted the Scottish Independence Referendum Act 2013, summoning the referendum, defining the question to be asked, giving the date on which the referendum was to be held, and establishing the rules governing the holding of the referendum. The Bill for the Act was passed by the Scottish Parliament on 14 November 2013 and received Royal Assent on 17 December 2013. Under section 36 of the Act, it came into force the day after Royal Assent."

Simple matter of record.