You can't unfreeze your ATPL unless you do an ATPL skills test, which is effectively an LPC after you have completed all the other requirements.
See LASORS Section G for all the details.
For info, I did 460hrs in 5 months so I could unfreeze on my first OPC/LPC.
The hours are there, you just have to ask for them.
So, when you're sat trying to keep your eyes open at 0500 with 3 hrs left to run from a night Dalaman wondering why on earth you asked for all these extra flights, just think of how much it would have cost you if you'd waited another 6 months. (You also get a quiet winter!)
The same goes for all the cadet entry/CTC people out there, it's possible to do the hours in 2 years, not 3, but it helps if you don't take loads of leave!!