What sort of area are you covering and what are you growing?
There are many things available from seep hoses that are laid out in flat rows, to nozzles on micro hoses that spray water in all directions.
All are used directly from an outside tap, some with a timer.

I have been using garden irrigation for many years, although, I didn't need to use it much last year.
I always use an online company named Blue Skies Water Systems. They have an American made system called raindrip.
Very easy to install, maintain and works a treat. My veg always does well with their dripline.

I have also installed a solar powered system from them.

I have called them a couple of times and I am always offered good service from a guy with lots of experience.

www.blueskieswatersystems.co.uk

Thanks for your answers. just had a look on blue skies water systems website and it seems fairly straightforward. Bonus - they've also got a sale on!

Before moving I made use of the Hozelock system. - A simple hosepipe with screw-in adaptors that lead off to supply water where it is required.

I currently use nature - it has been a wet summer for the last couple of years!

I purchased a set last year and of course didn't need it did I, although we had a hosepipe ban all summer the rain kept the garden quite wet and soggy! I got my irrigation set from greenhousesensation.co.uk, very reasonable and you could purchase add on bits too.