I am sorry to hear that you think your husband is suffering with depression and experiences panic attacks too.
I quite understand why you are concerned about your holiday. In order to get an official diagnosis I would encourage your husband to visit your local GP or healthcare provider.
If left unaddressed, these problems can get worse and there are all sorts of things that are available to help once a diagnosis is confirmed.
Provided your husband is not taking any medication, he could try taking St John's Wort, Hyperiforce if he would prefer to try a herbal treatment. This has been used traditionally for many years to treat low mood and mild anxiety. It generally takes a between 4-6 weeks to notice a difference so if he would like to consider this, it would be worth taking before you travel. However, please download the Patient Information Leaflet, as it is important to check whether or not it is appropriate for him to take it. Exposure to sunlight should be limited if taking it, so if you expect lots of sunshine on your holiday, this would not be the best choice of remedy. Please check with your GP or contact us again if you are in any doubt.
If St John's Wort is not an appropriate treatment, your husband could try Passiflora Complex which has been used traditionally to help ease stress and nervous tension. It does not have the contraindications known for St John's Wort so it may be preferable. It would be worth taking this before travel as well as it can take a week or two to feel the effects.
Flower essences can also be helpful as they can balance emotions. They also do not have any contraindications and can be taken alongside medication or herbal treatments. Mood Essence or Relaxing Essence may be applicable.
I hope this helps you to find the right course of action to follow and that you both have a relaxing and enjoyable holiday.