I would exercise caution here. It is not unusual for the hold on the funds to be removed prior to the amount being debited from your account (I work for a bank!!!). The chances are that this amount will come off in the next couple of days. Your receipt offers proof of purchase but does not prove payment from your bank account and the bank concerned would be within their rights to debit the amount should the error be spotted at a later date. Payments of this type are valid for 6 years and can be taken at any time during this period.
If the payment is not taken soon please query this with the holiday company and the bank. Believe me I have seen people caught out this way and it's not worth the hassle!
Hope this helps!