I was at Hammersmith Tech, studying Building and Engineering, the year we 'went metric'.
The Standard Method of Measurement for quantity surveyors had to change, as did all the sorts of calculations one needed in building and civil engineering. It really was a nightmare, and most lecturers were also floundering to explain how it all worked! I still struggle with 'Newtons'...
Like others here, I now work both in metric and imperial, preferring the latter really. I have all my dad's old tapes and engineering rules, so the allotment was always measured in feet and inches, and the garden at home still is as well! I had to design the work for planning permission at 'The Turrets' in metric though!
Funnily enough, I still cannot actually 'see' a measurement like a rod, or a perch, but a chain is easy as it's a cricket pitch...