At this moment in time providing you come under the same local authority then you can stay on legacy benefits, it is only if you move to a different local authority AND you need help with your housing costs that you would have to apply for UC.
Things will be changing as the Government want claimants to migrate over to UC but todate there are no details how or when this will happen.
As soon as we know Steve will put it in the Newsletter.
Gary
Nothing on this board constitutes legal advice - always consult a professional about specific problems