Hi Trevor
If you require a home visit then you need to submit a request from your GP saying that it would cause you physical and/or mental distress to go to an assessment centre. Only a small number of home visits are carried out. Without a request being submitted only a tiny number of home visits are given by the assessment providers and this is normally because someone has decided that it would be better for the claimant to assess them at home.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
