Complex sentence: The Bristol to Bridgwater section of the B&ER was opened to traffic on 14 June 1841, and on 30 June through running on the GWR between London and Bristol began.
Split into simpler sentences: The Bristol to Bridgwater section of the B&ER was opened to traffic on 14th June 1841. Shortly afterwards, on 30th of the same month, through running on the GWR between London and Bristol began.