Please post the UK rule that says you are relieved of "see and avoid" responsibilities (i.e., can fly "head down" so you can legally meet the Simulated Instrument Time requirements) when flying solo IFR and VMC.
Perhaps I am misunderstanding you (or you, me). If I am doing an IFR flight and I am in IMC the whole way for example, and then on descent I become VMC. I do not now need to acquire a safety pilot. I will be in VMC but I will still be IFR, and therefore IFR separation principles will still be applied (whether that's by radar, procedural, or 'big sky')
The rule that says that you must have a safety pilot if you are flying VFR but heads down simulating instrument flight still applies in the UK.
I don't recall coming across a requirement (in Europe) for simulated instrument time (nor do I remember seeing a requirement from it to be differentiated from actual instrument time. The definition I remember was along the lines of "flight be sole reference to instruments" which could apply in either simulated or actual).
to go back to this statement:
When flying under VFR, you CANNOT legally fly actual IMC, so the only way to log Instrument Time is Simulated Instrument Time with a Safety Pilot on board
Why can you not fly IFR?