EU Referendum: Official campaigns kick off

UK chancellor George Osborne on Brexit

The start of Britain's official 10-week EU Referendum campaign got well underway on Friday, with advocates from both the Leave and Remain groups battling it out to win public support.

On June 23, U.K. citizens will decide their country's future relationship with the European Union (EU), and whether they want to be part of a reformed union, or exit the bloc.

British Chancellor of the Exchequer George Osborne told CNBC on Friday the referendum is "a big democratic exercise" that helps to resolve uncertainty about the U.K.'s role in the EU. He said he hopes Britain will remain in the union and then "get to work on reforming the EU."

"We're clear — leaving would cause an economic shock and a long-term economic cost for the U.K. And that's one of the messages British voters are hearing," he said in the interview from Washington, D.C.

He noted that departure could deter investment in Britain and possibly trip up "one of the fastest growing advanced economies in the world."

Getty Images: Ben Stansall/Jeff J Mitchell | AFP/Getty Images News

On Friday, the former Labour chancellor, Alistair Darling led the march for the "Britain Stronger In Europe" campaign, telling the public that the "Vote Leave" campaign was "playing with fire".

The politician focused on the future of the U.K. economy and trade during the speech, saying any trade deal outside the single market would be "inferior".

"As a country whose long-term economic recovery relies on the health of our exports and our regulatory environment being attractive to global investors, it would be a colossal surrender of power to walk away from our largest trading partner, increase uncertainty, erect trade barriers and diminish our influence."

"It is a fantasy to suppose the day after (the U.K.) leave, other European countries will give us everything we want and ask for nothing in return," Darling said.

Skyline of London
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Meanwhile the "Vote Leave" campaign tackled the discussion of the National Health Service's (NHS) "funding crisis" on Friday and how it could be fixed by ending their EU membership.

"If we Vote Leave we will be able to stop handing over £350 million a week to Brussels and we will be able to instead spend our money on our priorities like the NHS. This will improve patient care," Vote Leave's chair, Gisela Stuart MP said on the campaign's website.

The group's claims that the U.K. hands over £350 million ($496.5 million) a week to Brussels have been discredited by the likes of the Institute for Fiscal Studies, with figures showing it's nowhere near as high.

The NHS however remains a hotly-debated topic for the public. Junior doctors have recently gone on strike over pay and working anti-social hours. Many have also complained in recent years about the NHS' overcrowding and under-funding.

The question of uncertainty

With many polls showing no clear decision for what Britain wants this June, the main issue that is putting citizens on edge is what the U.K. would look like if it departed.

"I think (a Brexit would have) a negative impact both on the EU and on the U.K.," Jeroen Dijsselbloem, Eurogroup's president told CNBC.

We need stability in Europe: Eurogroup president

"One of the main issues is that we need stability rather than instability in Europe across the board, political stability, stability at our borders, economic stability; we've had too much instability in the financial sector and the euro zone. And yes, we need to do a lot of work to improve how the EU functions and what it delivers for citizens; and that I think is also a key issue in the U.K. debate."

The "insecurity of what Europe actually delivers" has been at the forefront of people's minds in recent years, said Dijsselbloem, mentioning the financial crisis as a key turning point for EU members, on whether further European integration would be a beneficial move.

If Britain does decide to leave, its economy could see a weaker currency and potentially higher interest rates in the long-term, Russ Mould, investment director at AJ Bell, told CNBC Friday, which would mean holidays and imports could be more expensive for the U.K. consumer, he added.

UK should leave this 'very expensive club'

Despite all the potential benefits and costs of leaving the EU, at the end, it will be up to the British public to decide whether to take a "leap in to the dark" or not.

"Brexit will be determined based on passion versus fear," Alastair Newton, co-founder & director at Alavan Business Advisory, told CNBC Friday.

"And in the end, I still think that the majority of British voters will go into the polling booth, maybe thinking when they get in there that they're going to vote to leave, but then they're going to say 'Actually, I really don't want to take the risk'."

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