I am doubtful that you will find a cheap travel insurance policy covering health when you are over 70.However it does depend where in Europe you are going.If to the UK we have reciprocal rights with the NHS so you will still get medical care.There are other european countries that have some form of reciprocal arrangements-Italy I am sure is one.I suggest that you get in touch with the HIC and get details of what is available.Then you will only need a basic policy for theft,cancellation etc.
For everyone you should always read the fine print and see what is covered.The number of kiwis i have seen,thinking that they were covered by their travel insurance when all that is offered is treatment in a public hospital which they are entitled to anyway,is amazing.