Dark Sky Sites
For those of us living in North Manchester, our closest area with decently dark skies is the Forest of Bowland north of Clitheroe, and further north the Yorkshire Dales and Lake District away from towns. For people living south of 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.
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 dark sky locations UK wide, and helpful advice.