D
I can't give you a definitive answer as this is not an area of benefits that we support but there is no Assessment Rate for Universal Credit, while you wait for your WCA you are moved out of the All work-related activity group and if fail your WCA you are moved back into this group. On this basis your HB element should not be effected.
In old style terms, you are currently claiming ESA, if you fail the WCA then you in effect make an immediate claim for JSA.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
