Should add that a cable break can be a little worrying though, especially if it's your first solo flight

The way I was tought was to assess the height and either land straight ahead or perform a "short circuit" to come back in and land

Yep. First thing is not to rotate into a steep climb until you are high enough to sort it out if it does fail and until you are happy the glider is fast enough and accelerating normally.
If it breaks, lower the nose quickly and establish approach speed, check the cable has gone and assess where you can land. Typically, the options are straight ahead if you're low, turn downwind if you're too high for straight ahead and maybe continue the turn and land across the airfield or, if you have plenty of height, a circuit and back to where you launched.
It can bite you on the @rse, like most flying activities, if you rotate too quickly into a steep climb, or if you try to manoevre before recovering a safe airspeed.
Here's how it should look:
http://www.youtube.com/watch?v=y8FP_MIB7gw&feature=relatedKevin