It was booked in for 8am and so given the "limp mode" situation, I set off at 7.20am.
The plan to take the A20 but I ended up on the M20. On two hills out of Hythe I was down to 10mph flat out. Once on the motorway I got up to 45mph.
It turns out that the problem was that the pipe from the turbo had split. Parts came to about £240 and labour even more. With VAT added, the bill came to £676! Gulp.
At least it is back.