Need to find a system for watering

We were away for nine days and there was a bit of a hot spell whilst we were away.

I hadn't seen the neighbours to ask them to water the few bits on the remains of the grow house (I have taken the cover off).

I knew I would come back to devastation as the aubergine and chilli's are in pots and the tomatoes are out stripping the confines of their grow bag. I have never really looked at watering systems, I wouldn't know where to start and not sure that it is an expense I am willing to pay for a few items. I suppose I could look at low tech Heath Robinson style methods for getting around not being able to water. So let me know what you do to get around the need to water while away.
Luckily I watered them in the nick of time when I got back and they have resuscitated fairly well they are more resilient to such abuse than I thought.