Is there any simulation environment provided with TDC-GP1 counter frimwaire?
Not sure about TDC-GP1, but if you need IBIS model for your TDC, you can have a look at TDC7200 IBIS model.

If you are actually looking for SPICE simulation, beware the internal structure of a TDC does not lend itself very well to SPICE simulations. The universities which did a lot of research do not seem to include the TDC in their simulations Oulu: simulating the comparator before the TDC and Lund: simulating the laser diode.