“What will happen if the UK decides to leave the European Union after the referendum, and where will it leave us expatriates?”
“With millions of British expatriates living in Europe – the majority of them in Spain – many with businesses, property and family to consider, there are major concerns over the repercussions of a vote to withdraw from the EU.”
Mr Shapps feels these are consequences we are not going to face:
“My personal opinion is that the British people will vote to stay in the EU. Not the EU as it is now, however, but a re-modelled EU, an organisation more like the old Common Market that we signed up to originally after the previous referendum in 1975.”
He also assures expats that the FCO has started making sure information will be accessible and:
“I wish to impress on the expat community in Spain how important it is to register to vote. We are going to scrap the 15-year limit on voting, we promised that in our manifesto, but people living in Spain will need to register with their last UK local council to be able to have a voice in the referendum. It’s very important.”
Source: Euro Weekly News
Unfortunately, this is still not a government commitment to scrap the 15-year-limit on voting before the Referendum and why those EU resident British expats not yet excluded, should register on-line to vote on https://www.gov.uk/register-to-vote.
Votes for Expat Brits blog 
What is the point of registering to vote when the voting forms arrive either 2 days before the election (mine and obviously no chance of sending back in time) or a week after (my husbands) the election date? This happened to us at the last election and I believe many other ex-pats have had the same experience.
We agree and the problems experienced in trying to vote by many British expats such as you and your husband, have been fed back to the Electoral Commission and reflected in their subsequent report, together with their action plan for improvement next time around.