I can think of four options.
First being a screw on your electrical socket panel, these are earthed. Simply unscrew one, add a slip ring, re-screw and you have a ground point.
If your parents do not let you do the above (as mine did) try:
The other option is your plumbing. Attach to your copper piping, this is also earthed. I should imagine you have a radiator in your workspace, if so the exposed copper pipe here is a good point for attaching.
Other options are connecting to an already earthed frame, dvd players, tv's, computer ground planes come to mind.
If you have none of the above, run a wire to your grounding rod, often a copper cylinder, with a yellow-green earth wire attached. Attach here, run back inside to a connection point, and attach wrist straps.
Be very careful, you do not want to connect to a live object, but so long as you connect safely to ground and you use a 1MΩ resistor strap, you should not encounter electrocution. Never give the "grip of death" a chance, always check connections with the back of your hand, but double check first.