Complex sentence: After the airing of the first series, the local council became aware of the renovation work, and raised objections that the work did not comply with planning regulations, forcing the couple to apply for retrospective planning permission, and make fire safety improvements.
Split into simpler sentences: After the airing of the first series, the local council became aware of the renovation work, and raised objections that the work did not comply with planning regulations. That forced the couple to apply for retrospective planning permission, and make fire safety improvements.