The part that I am more concerned about is the grey area, where you are above cloud, the forecast was for broken or scattered at 2500 and on arrival it is solid with no holes, and even though the base is at say 2500, you have to get through (if you are intent on landing). Knowing that the rating doesn’t allow for this, what is the correct procedure?
Maintain VFR and either go back to get under the layer in VMC or divert to somewhere you can land at within your licence and rating privileges. If you can't, declare an emergency. It's black and white. Sorry if I am being dense, but what is "grey" here?
There is nothing special about flying VFR on top that "sort-of-kind-of lets you do a bit of IFR" because inevitably you might need to sometimes. It's just plain vanilla PPL VFR stuff which happens not to be permitted in the UK, but is in many parts of the world, and the majority of the world's PPLs (ie. FAA PPLs) manage fine.
There is a paper here: http://www.pplir.org/images/stories/...t%20review.pdf
that discusses the consequences of pushing "marginal" conditions and flight rules.