If you are looking for some rides for "training" there's not a lot to beat a 100km organised ride - and loads are available supporting a good cause ...
. . . here's a few this summer ;
MacRide - Tour : 30 April - 1 May 2011 - fully supported, two days from Stratford, London E15 to Stratford-upon-Avon
MacRide - Elgar : Sunday 15 May 2011 - 60 miles or so from Worcester in glorious countryside
CTC-Heart of England Audax rides : Saturday 21 May 2011 - 100 or 160 km starting at Meriden
Wheel Heroes : Sunday 22 May 2011 - 100 km or 100 miles at Stratford-upon-Avon
MacRide : Sunday 11 September 2011 - 60 miles around the quiet lanes of Shakespeare's Warwickshire
. . . and don't forget that there loads of Audax rides too