Does your husband's Oxygen provider not have a POC he could use on holiday as this would save you renting one.
Someone mentioned not being able to take NHS ones abroad. This was the very reason I was first supplied with one - so it would cause no problems on plane and resort. I was given an Imogen XPO2 which I loved but sadly had to revert to Liquid Oxygen last year when the XPO2 was no longer giving me sufficient Oxygen.
I am now using 5 litres Ambulatory and this us why I am going to be renting a POC from PureO2 (their Eclipse WILL give me 5litres).
You just need to supply a letter or email from your Respiratory Nurse to state you do require Medical Oxygen.
As for INSURANCE - I always use ALL CLEAR as they have always proved to be the cheapest with good cover.
One thing, if you do not declare COPD and you require treatment for ANYTHING, your insurance cover is void. It is always best to declare ALL Medical problems.