If you plan to use your credit card after your trip its worth noting how your monthly payments are allocated... I think you might find 0% doesn't quite mean 0%
From the halifax website:
2.4 We use all payments you make to pay off your balance in the following order:
(a) Transactions that appear on your statement, starting with those on which we do not charge interest (for example, any Government stamp duty), then those on which we charge interest at the lowest rate and so on up to the highest rate of interest;
(b) Transactions not yet shown on your statement in the same order as above. In this condition, “Transaction” includes the amount of the Purchase, Cash Advance or Balance Transfer plus any interest, fees or insurance payment charged as a result of that transaction. For example, a Cash Advance fee is included as part of a cash transaction. If a payment is not enough to pay all Transactions charged at a particular rate of interest, we will use the payment firstly to pay off any applicable Government taxes or charges (including stamp duty), the interest, then any fees, insurance and finally the amount of the Purchase, Cash Advance or Balance Transfer within that interest rate band.
So I interpret this as the following: you have an outstanding balance of €2,500 and new transactions of (for example €400). You pay €500 each month. This reduces your 0% balance to €2,000 but you still have to pay interest on the €400 new business. This will happen every month i.e., 0% part gets smaller but the the amount you are paying interest on increases.
In other words if you plan to use the credit card at all over the 6 months you will end up being charged interest until your balance is reduced to 0.