Swallow Boats rally at Rutland Water. Note that engines are not permitted at Rutland Water but you can sleep on boats moored at the pontoons. See forum topic for full details:

http://www.swallowyachtsassociation.org/smf/index.php/topic,664.0.html

The following contact details can be used to find out more about sailing on Rutland Water in general:

Tel: 01780 460154
Email: rutlandwatersports@anglianwater.co.uk
Website: http://www.anglianwater.co.uk/leisure/what-to-do/watersports/