The closest thing from the HI store that would meet your need is stucco. Stucco is a fine grained portland cement product and would be suitable as a plaster scratch coat. Finish coats of plaster are lime mixed with plaster.
If the brick will be permanently covered, it might be better to just attach furring strips and screw drywall to the furring strips. This approach would certanly be easier to achieve a smooth consistent appearance with the other walls, and could also be used for hanging artwork, shelves etc. True plaster work is not a real good DIY project, which may be why you are finding it difficult to find materials.