Nothing beats trying it out at home first, that's not always so easy. So you got a good one.
I cannot use the 10LUT therefore I am restricted to sRGB
Two different things, don't mix them up. You can use whatever monitor gamut you want, irrespective of that. And unless you specifically need to restrict the unit to sRGB because you need to use software that isn't color managed, it's always best to use the custom setting. This leaves the unit in its native, unrestricted state. Build the calibration and the profile from that.
(I assume what you mean is that you can't hardware calibrate directly to the monitor LUT. For that you need the i1 Display Pro sensor (i1D3), which is the only one the Dell software will accept).
Just so it's said, for web you'll need to use Firefox with color management set to mode 1. No other browser is usable with wide gamut.