You should organise your Travel Insurance as soon as you have bought your airline ticket. The insurance should cover your air-ticket refund etc in event of your trip cancellation for reasons beyond your control, e.g. medical, security etc.
The guidelines for insurance cover are: 

Type of cover + Indemnity / Sum Insured

  1. Medical and additional expenses including repatriation.
  2. Cancellation.
  3. Personal liability.
  4. Personal Accident (death and capital sums) .
  5. Baggage and personal effects (check single item limit if any).
  6. Cash
  7. Legal expenses

Please make sure that your insurance includes cover for Medical Evacuation  in case of serious accident needing ambulance, air-ambulance, or urgent flight home.

We use Endsleigh Insurance, and we've put a link in below. You can ask other insurers also...