You can go and buy a auto feeder but not sure how the settings are, best if you can find some one. Look for pet minders in your area.
Do not know where you are so can not help there.

I'd just leave them to their own devices especially if the pool has plenty of water plants or waterlillies growing in it and it is a fair size and not under filtration. If they die then they are easy to replace but in a decent size pond, say 2m across by 400mm deep they should be able to "live off the land". You also need to think about evaporation which will average out at maybe 4mm per day and if you have some device to keep the water level topped up you may find after 6 months the water will full of minerals from tap water especially if it has bore water mixed like in Toowoomba.

Good Luck.

As hako said water evaporation is a bigger problem than sustenance - you may need to fit a C*ck valve (you can get them off old toilet cisterns) . we put two feed blocks in with six Goldfish and go away for 8 - 10 weeks (in pond one and a half metere long X one metre wide). We do have water lillies and water weed growing in submerged pots - we also add a 75mm water algae slow release block - the fish are now 13 years old.

Ask your local pet shop if they'd like them. Do you know anyone that you could pass them on to? Look on the internet for Goldfish recipes, they're edible.

We have 2 goldfish in an outside fountain pond. Got them at least 5 years ago if not more to eat the mossie larvae. Allow some algae to grow in the pond and you'll find they eat that. That's what we have done. We can go away for quite a long time and they are fine. I usually throw in a couple of 3 week food tablets and they are there still when we get home. Water top up will be your issue.

As an aside apparently the Ararat Jail discovered there was a fish pond in the grounds when they resurrected the site. It was a huge number of years that the fish were there and had grown to a huge size.

Di