I thought conservatories were a specific exemption to this. Does anyone
know
for certain?

In case it makes a differerence, the floor area of proposed conservatory
is
approximately 11m2. The ground floor area of house (terraced) is about
36m2,
giving approx 72m2 total area on two floors.

Christian.

You will need both planning permission and building regulations approval if
the conservatory is attached to the house and it exceeds 10% of the existing
floor area. Note that because it is a terraced property the size limits are
smaller.