Yes, the "sight of surface" requirement (of a UK issued PPL) for VFR disappears if you have an IMCR or an IR. It also doesn't exist for most foreign PPLs, and doesn't exist in most foreign airspace.
I think (and I am going to get jumped on for saying this) one needs to be more practical about this stuff.
For example, no use asking for an RAS (available only to IFR traffic in Class G, IIRC) when you are in VMC. I know a plain PPL can fly IFR in VMC in Class G in the UK but they are going to vector you all over the sky. You get ludicrous doglegs, mostly around unknown
non-transponding traffic, often microlights pottering about at 600ft and perhaps 4000ft below you, but the radar can't tell so they have to give you avoiding vectors. I've had it done to me once or twice, years ago, and it's a really pointless exercise. The traffic reports one gets from an RIS are just as useful in practice, especially if after a report like "contact at 12 o'clock, 1 mile, recip heading, same level", and you are sitting in IMC, you say "Gxxxx, turning right 20 degrees" and do it right away
The next thing is cloud separation if above clouds or if above a certain level (which I cannot ever remember). The rules do not apply when climbing or descending (obviously) so when do they apply? How long do you have to be flying straight and level before they begin to apply? It's slightly pointless to worry about it. If you are flying IFR, VMC on top, under say ATS direction (say in Class D) and they give you vectors, you aren't going to suddenly say "sorry, can't comply because I am only 100ft above the clouds".
Whereas something like a plain PPL flying straight into Class A at FL120 on an airways flight plan is something altogether different, quite absolute, a 4-digit fine and a licence pulled. As a result, it's never been done