A relative has a passport due to run out in 3 years. He is off to Australia and New Zealand and will probably return just before the passport runs out. However if he does need to renew it in either Australia or New Zealand how difficult would this be? For example if moving around finding someone to sign for him. Where would he have to go to? Is there any one out there with knowledge of the systems in those countries or has experience of passport renewal.
Your passport can be renewed at a British High Commission, etc, in either country. The cost is likely to be rather more than doing it at home, but otherwise it's easy and probably quicker than doing it here.
If you are still recognisable from the old photograph no countersignature is needed.