Trespass here is actually any interference without permission. The piece on causing fear just means it moves from a civil matter to a criminal one under the Criminal Justice (Public Order).Roofers, utilities guys, gardeners need access to gardens all the time.
The Land And Conveyancing Law Reform Acts deals with access for maintenance. In such cases where the owner of the property you need access to does not explicitly consent, you must request a Works Order through the courts.