We are planing to install an Xpelair C100HT Humidistat extractor fan in the bathroom and wanted to connect it directly rather than using switched live from the lighting circuit. But we are planning to take feeds (L and N) from the lighting circuit (ceiling rose). The reason is we need to use the shower/bathroom during the day times and do not need to have lights on. Xpelair's proposed installation is also similar to this. I have attached it below. We are not going to add the optional lamp in the circuit, but planning to use a FCU (DP) with a 3A fuse as the fan isolator.
We are very grateful for your views and advise on this.