Council Tax- exempt property?

Not sure where this belongs really so am posting it here.

Client has succeeded to her (deceased) mother’s LA tenancy. Client is still under 18 so a relative is apparently standing as guarantor in relation to this (I’m not sure of the ins and outs not being a housing person). Client lives in the property alone with relatives checking up on her regularly, and is in process of claiming IS (in relevant education).

She should be fine for HB but the issue is what happens re CT? She’s under 18 so not liable for CT (and in any case is a student). So who is- or is no-one liable? I can’t quite get my head around it. Will the LA not set up a CT account in relation to the property at all or will they set it up in the name of the guarantor relative (who has a tenancy elsewhere)? And if so, who is liable for the payments?

The dwelling should be exempt from Council Tax under Class S: not empty, but no-one over 18 resident.

Thanks HB Anorak. Knew you’d know. Appreciated.