Yes you can have brick sides if that is what your house is. "Materials used for the loft conversion must be similar to the existing house" or similar wording.
We have a rendered loft extension which matches the rest of the house that is rendered (I don't think it was built rendered but I'm not 100% sure, both neighbours have different houses).
That would be the nicest for us I reckon but no idea how much extra it would cost.
Can't quite bring myself to do the tiled box, the house looks nice from the outside at the moment and I'd hate to think I made it look ugly (and spent a bomb doing it)
Yes you can have brick sides if that is what your house is. "Materials used for the loft conversion must be similar to the existing house" or similar wording.
We have a rendered loft extension which matches the rest of the house that is rendered (I don't think it was built rendered but I'm not 100% sure, both neighbours have different houses).