I employ this role in the NHS. So if it is NHS then: the written will likely be looking at how you write, good grammer, can spell etc. You would be expected to follow the NMC guidelines for documentation and record keeping. (this document is on download at the NMC website)
the group exercise could be a scenario from the workplace with the "how would you manage this?" type question. Or it could be a team building / problem solving scenario. A recent one we've used has been discussing our responses to the panorama expose on winterbourne but that is specific to the field of LD. I would advocate that this will be how you work in a team and your contribution to the team.
I will be attending an interview for a clinical support worker post and they have stipulated it will be in the form of a written test and a group exercise. Does anyone know what I can expect and how I can prepare for this? Thanks in advance.