In reply to Adders:
I'll show you my cycling shorts when I next see you, then you will know what you should be looking for ...... Lycra jobbies which go to the mid thigh, with a chug off chunk of foam to cushion the pieces
Spring/summer, you shouldn't need to wear anything else beneath/over them (other than a pair of wicking knicks, imo!) but in winter, you can wear a pair of Ron Hills under them to keep extra toasty and warm. As John said, Wiggle are good but also try these;
http://www.cyclexpress.co.uk/products/Womens_Cycling_Shorts_1009.asp
...The 'Curve' ones are also very good but a bit more expensive.
Looking forward to getting out on the bike with you this spring