What will a CCTV survey show?
CCTV surveys will give you a brush’s eye view as it ascends and descends through the chimney. This is important. OK so fumes have been escaping into the bedroom chimney, and so the chimney needs lining. However if you just reline blindly, you may find that lining material is pouring down the bedroom chimney, because it wasn’t just a crack in the flue, it was a gaping hole in the feathers where a couple of bricks have fallen out. If only someone had taken a look before the job had started.
There are of course other tricks that CCTV surveys can help with. Can’t the sweep get the brush up the flue? Don’t break into the flue blindly, have a look up the chimney. The problem may need another approach, and it’s nice to know that before you go ripping holes in the walls. In short, look before you leap. It’s cheaper in the long run.