While Windows has Location services built in, I’m pretty sure it uses your ISP’s IP address [allocated to you] as it’s means of identifying your location, and this can (and probably will) be wildly inaccurate. For example, I’m located in Somerset, UK, but my IP address usually resolves to Outer-London.
If all your concerned with is setting Sunrise / Sunset times, this probably won’t matter, as all of the UK resides in the same timezone, so wherever the Hue Essentials app gets it’s info from, regarding those times, there won’t be much of a variation.
If however, you plan on using home automation; i.e. Lights turning on/off when you leave home or return, your going to need a more accurate point of reference. Your also going to need your phone, as it’s the beacon the Hue system needs to ascertain when you are indeed ‘home’.
A combination of GPS and local cell tower triangulation would be used in this instancce (more likely the latter rather than the former, since GPS doesn’t work so well inside buildings, especially multi-storey ones).
If your usage scenario is the first case, rather than the second, you ought to only need to set this once. Thus once your home location is determined, and ‘set’, turning off location services (on either the phone, or Windows) shouldn’t have any bearing on the ‘sunrise / sunset’ events successfully triggering in so far as I understand it.
Gib.