Chancellor George Osborne has warned Britain cannot be "immune" from the fall-out from the Greek referendum.
Prime Minister David Cameron will chair talks with Mr Osborne and Bank of England Governor Mark Carney tomorrow morning to assess the impact of the poll, which could see Greece become the first country to be forced out of the euro.
"Whatever Greece decides, Britain is prepared. We have the plans in place for whatever the outcome is," Mr Osborne told BBC1's The Andrew Marr Show.
"I don't think anyone should be in any doubt - the Greek situation has an impact on the European economy which has an impact on us. We cannot be immune from these developments.
"That's all the more reason why we have to keep our house in order, run that Budget surplus, pay down our debts be better prepared for whatever the world throws at us.
"I think there is a lot of sympathy I suspect in Britain and elsewhere in Europe for the hardship that the Greek people have endured. It's not their fault. It's been the fault of some pretty terrible governments they have had in the past.
"Of course we want Greece to prosper and succeed - it's a country we feel a lot of affection for. But ultimately if you are in the single currency, there are rules you have to follow."
Voters in Greece are going to the polls after the radical left Syriza government decided to put the latest austerity package from the country's international lenders to a popular vote.
Prime minister Alexis Tspiras is urging people to vote "No", insisting it will give him a mandate to go back and negotiate a better deal - but opponents warn that will trigger a catastrophic financial collapse.
Rallies have taken place across the UK over the issue, while British tourists travelling to the country have been advised to take cash with them and be wary of their personal safety.
Many Greeks living in Britain have returned there to vote, while those who are unable to return at short notice say it is "always on their mind" as their concern for family members grows.
Greek citizens living in the UK could only take part in the referendum if they returned to Greece to cast their vote.
Rallies have been held in London's Trafalgar Square, Leeds, Liverpool, Bristol and Edinburgh, with another today in Manchester.