Personally, with a lot of experience, it's on a scale - perhaps 1000ft agl for a slow aeroplane in the local area, 2000ft for faster aeroplanes and longer trips over most of the UK, nearer 5000ft if I'm crossing the Pennines or Snowdonia. I'll accept lower cloud if I'm in an aeroplane I'm prepared to go IFR in (something a new PPL won't be qualified to do), and the cloud temperatures are likely to be consistently above freezing. Also consider visibility, which can be quite important, particularly on longer trips into territory you don't know: I'd accept 5km for local flying in a slowish aeroplane, or where I'm just transitioning to IFR anyhow, but I want 8km+ for faster aeroplanes or cross-country flying. VFR visibility minima are very low, and don't usually go near them unless I'm just treating the trip as IFR anyhow.
I'd suggest a new PPL, needs to be using higher limits than I do - perhaps 2000, 3000, 5000 - and most of the time 10km+ visibility.
No, Skydemon won't tell you if you're within your personal weather limits, that's a matter of judgment, experience, and multiple information sources - including looking out of the window. It may have an option to claim to do so, but only a fool would rely on that, just as only a fool would recommend a new PPL flies in conditions close to VFR minima.
G