A wood-paneled north wall indicates uncompleted plans for further extension.
The building is aligned north–south rather than east–west, and the porch faces east.
That 'apse' is to the right, which intuitively should be liturgically east, and contain the sanctuary; but it is screened off, for use as a sacristy.
It is all that remains of a round tower, one of Suffolk's few modern ones.
This article about a Roman Catholic Church building in the United Kingdom is a stub.