There did not seem to be any point in re-thinking the costs some more so I got the amp sent off and let Bruce know.
I earnestly hoped that once it was at his shop its mere presence would command attention and I could get it back within a matter of weeks.
Early indications supported this (see part 28) but in the long term, how wrong I was.
Having already wrapped it over the weekend using most of my stock of packing materials, I think I'll go with plan A. I'd hate to take components out unless there was absolutely no alternative.
I've send it today by UK ParcelForce Global Priority service (not so expensive) and it takes about 5 working days. I have a tracking number which I'll check periodically. I've marked it as you suggested re: customs so... here's hoping it arrives OK.