Board up hole in kitchen chimney breast?

[jmiah]

Just moved into a new house.
There used to be an extractor fan fitted into chimney breast in kitchen. I've removed the extractor as have no use for it given the range has been moved to other side of kitchen (pre my ownership). There's now a hole in the chimney breast as you would expect. When I removed the extractor there was no ducting used, just wires going into that hole. Looking for advice if I can just board that hole up with some timber? Could that cause any issues in future with ventilation etc?
See attached picture of when extractor was still fitted and picture of it now having been removed. I've taped up the hole for now given debris coming through. Any help much appreciated.

 

[Wayners]

Unless you block off chimney outside you will need a vent to keep air flowing

 

[ree]

Poster #2,
Presumably the "chimney outside" you mention is the flue terminal in the chimney stack?
Why would the OP want to go on the roof to "block" off the flue?

 

[ree]

OP,
Block off the hole, chimney sweep to sweep the flue and then fit a vent in the front of the chimney breast.