Hornbeam also provides a good hedge and is naturalised in the same way as beech (i.e. is not a native, but has been here for a long time). Beech is not a native species, but may once have been! It's slow growing though. In terms of speed, ash grows like stink once it is established.
I planted a griselinia hedge around my garden boundary nearly 20 years ago, and ive kept it trimmed to a height of under 5ft. Its no bother and growns and fills out after a couple of years.
Thant's good advice from sydthebeat. I'd steer clear of all conifers. Escallonia too makes a lovely hedge and has lovely red flowers that last for many weeks.
We have Laurel which everyone admires just needs to be trimmed once a year. I have seen a lovely hedge of "Red Robin" (common name) -don't know proper name for it, beautiful colour, its planted as a hedge in a housing estate nearby. I have it as a plant in the garden.