To turn water of on pole you need some sort of pole valve. Gardiners do one for about £10 which fits into the pole hose, designed for hose internal diameter 5mm, external 8mm. If you use a thicker pole hose they sell an adapter.
When I use this I just hold the pole hose in my hand along with the pole and find it easy to turn on/off.
There are other options and it really is a personal preference thing.