There has been recent articles in the UK press on Greece and the country's current financial situation. 

Speculation about a possible Greece debt default, and potential exit from the Euro, has been current for some time, but at present remains just speculation.

Any changes would be highly unlikely to happen overnight, any switch to a new currency would take time and Euros would likely be accepted in the interim.

Holidaymakers heading out to Greece this summer are advised to take some cash in Euros with them as well as other payment methods (credit/debit cards) so that they are covered for all situations.

We would also advise them, as we would with any destination, to take out travel insurance as soon as they book their holiday to provide protection should they need to cancel.

We do not anticipate that there will be any need for tour operators to rebook their customers to a different destination. At present we have no indication that holidaymakers will be disrupted however, as with all destination matters, we will continue to monitor the situation and work with our Members on any developments. This is an unusual situation but the industry is experienced in handling unusual situations.

Source: http://abta.com/news-and-views/news/abtas-statement-on-greece