Hi Robby
Yes, the DWP has a backlog, so it's almost impossible to say how long you might have to wait. We have had members of B&W who have waited 18 months for an assessment after they sent a review form in. The only way to get some sort of timescale is to ring the DWP and ask if they can give you an update.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems