Hi Jezze,
In the current version of LR (1.6.342), it is not advisable to play a big playlist like the one you've described. This is because LR would have to use up too much of your computer's resources in playing it back. We hope to address this issue in the next version of LR, though, but in the meantime what I can recommend for you is to trim down your playlist.
You can split your current playlist into smaller parts and just play each smaller playlist one after the other -- this way playing these won't cost too much on your computer, and LR will not crash too often.
I hope this helps!