Hi Captain Vicky

Yes, I had ectopics on & off 24/7 for a number of years throughout perimenopause & well into post & had the whole range of tests to arrive at that diagnosis. They are truly horrible, very unnerving & I feel for you. You already know a lot about them so I won't do a long post (for a change!) but can I suggest you put palpitations, ectopics or irregular heart beat into the search box to see some of the many threads in which we've discussed these before? You should find tips, solidarity & reassurance there at least.
In answer to your question as to what helps - for me it was starting HRT shortly after a change in thyroid medication. Seems likely it
was the HRT that calmed them, as with each change of regimen while I've been trying to find my best fit, the ectopics have returned to some extent, though thankfully only briefly. That said they do also tend to resurface for a while with changes of thyroid medication, but experience tells me the very worst, years-long episode of these I went through was primarily menopause related.
I hope your Cardiology appt will help get them sorted for you. Let us know how you get on if you have time?
Wx