This study of the chlorination of alcohols by Clark and Streight, from Transactions of the Royal Society of Canada Section III, pp 77-89 (1929) states that the best yields for the chlorination of benzyl alcohol aren't when heating is used, but quantitative yields can bee achieved in the cold, using a ratio of 1 BzOH / 2 ZnCl2 / 2 HCl ;)
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_imgs/djvu.gif)
;D
Now as far as your problems in purifying halide compounds, first you must consider the nature of the reaction. The organic halide is probably going to contain some of the acid used to produce it, thus washing with a basic solution to remove these acidic impurities is in order :P Many metals are destructive to these halides, so you must prevent exposure; vacuum distillation is the recommended technique for final purification :)