Depends what the Reed job is. Also the hours of that job might not fit with yours anyway. So too many variables to really offer advice. Hopefully your current job won't keep stringing you along for too much longer. I think the chance to get HR experience is a good one but you need to know they are serious. Find out a bit more about the Reed job and whether that is temp or perm and just tell them that you are waiting to hear about hours from your current role and see what they say.