THE whole of Herman's Hermits' cabaret act is to be filmed while the group is appearing at Batley Variety Club during the week commencing February 8. Object of the exercise is to prepare a 45-minute film which can be leased to smaller clubs - who could not otherwise afford to book star attractions - for screening to their patrons. The New Seekers' act is also being filmed for the same purpose, and other big names are being lined up for this project.     The company behind this new venture is Starvision, who expect also to fnd a lucrative outlet for these cabaret films on the overseas market. An initial survey in Britain indicates considerable interest among the smaller clubs, and many provisional bookings have already been taken.     Herman's Hermits - whose new Columbia single "Years May Come, Years May Go" is released today (Friday) - have already recorded a sequence on the new disc for BBC-1's "Top of The Pops." They also guest in the same channel's "Crackerjack" on Friday, February 13.