Suggestions for Irrigation Systems

I'm trying to ease the watering burden on the in-laws for when we go on holiday.

We have a lot of tubs around the back of the house that need watering regularly. Ive tried drip systems on water butts but these tend to clog or are not easy to regulate - they seem to be all or nothing and no timer.

We don't have an outside tap near the area so cant currently fit a timer to mains water.

There are two main areas to water so two systems would be needed.

I'm thinking battery or solar powered pump / timer but have no experience of their effectiveness.

Does anyone have a setup that would work in this scenario ?

Any suggestions welcome