It's not a question of actively seeking employment (ASE) as you can be ASE at any time but it is what is called Availability i.e. availability for employment. You must be willing to attend an interview if given 48 hours' notice and willing to start employment if given a week's notice (this is more than normal since you and the organization will need to make alternative arrangements.) It's not a case of giving up the volunteering if the right job came up, you must be prepared to apply for and accept the offer of suitable employment.