Lough Neagh lake in Northern Ireland is a nice conserved recreational park devoted to sports. Accessing from Lurgan you will find a beach that curves giving several sideshore directions. Flat to choppy water.
There are also other spots around the lough. For example, Cranfield in the north end (towards Antrim) is an option. However, it is exposed and gets big swell during gale force winds, so naturally stay away in strong winds.