Good morning!
In the UK, Class G, an instrument qualified pilot can enter IMC, because IFR in Class G does not require radio contact.
Outside the UK, this is a grey area because there is no possibility of a clearance in Class G anyway.
This is no grey area outside the UK, it is plainly and simply forbidden. In class G airspace, you maintain VMC. If unable to do so on your intended route, you turn back. If unable to turn back, you declare and emergency and will receive immediate climb clearance and vectors away from traffic and obstacles.
Every IFR clearance for a flight originating in class G airspace will contain wording similar to this: "IFR starts passing 5000ft,
maintain VMC until 5000ft". If unable, you are supposed to tell someone. Or risk crashing into mountains or other traffic instead.
When will this kind of accident ever stop happening? It is totally unnecessary to kill yourself and your passengers in this way. Only to save a few minutes circling while your IFR flight plan gets processed. Or to save the trouble connected to the (possible) consequences of declaring that you have already entered instrument meteorological conditions and need assistance
now. With or without flight plan and clearance. Over the years I have seen far too many of these accidents.