Here goes.
At night you can only fly IFR, except that you can fly SVFR in a Control ZONE. The class E bit near GLA is a control AREA as it doesn't begin until 2500ft. So you have to be IFR at night.
In a class E control zone you could get SVFR at night. And as it is night any traffic in there would have to be either SVFR or IFR so you would get standard separation. It is only during day that you are permitted to enter class E airspace VFR without clearance.
Do you fly out of Cumbernauld? If so please give Glasgow a call on 119.1 if you are flying under or in the class E airspace. We honestly don't mind as it makes our job of getting the big stuff into Glasgow easier if we know what you are doing.