I sat an Instrument Rating test in India many years ago. The glide slope was lost and I went around, continued with the test. During the debrief the examiner asked if I had considered converting the the approach to a localiser only approach. It was my first ever rating so I was rather nervous and the thought never crossed my mind. I of course replied no and was told that both going around or converting the approach were correct if the localiser only was listed and briefed.
The examiner was from the Dutch RLD.
I believe therefore you can switch if briefing carried out during initial brief.