Dark Sky Sites
To find your own dark sky areas take a look at this World Light Pollution Map which is zoomable right down to local level - red and orange are bad light pollution, green so-so, blue and grey are good.
For those of us living in North Manchester, our closest area with decently dark skies is the Forest of Bowland north of Clitheroe, and the Yorkshire Dales a bit further north. For people living in south Manchester, maybe Snowdonia is easier to reach.
For those not wanting to travel so far, the sky is fairly dark overhead on the West Pennine Moors north of Horwich, the South Pennines north of Todmorden, and the Peak District east of Glossop. However, with these places the proximity of big cities means there is a lot of sky glow above the horizon even if it's dark overhead.
It's also worth looking at Dark Sky Discovery Sites - there may be one not too far away from you. Forest of Bowland AONB normally hold a number of stargazing events during the year. See Forest of Bowland - Stargazing for more information. Also, see Go Stargazing for events and locations UK wide, and helpful advice.