The cam belt needs doing anyway so you can't include that as a trip cost.
We've done loads of trips through Europe (wife is from Bilbao, she was living near the Hauge when we meet and her kids were there for 3 years after she moved over/several touring holidays - last was Naples, next is Rome) so have a bit of experience, possibly 30k.
The only additional equipment I take is breakdown cover and the only things I have needed were a temporary mirror after someone took one off the Range Rover and some sun tan oil when the fuel filler cap lock dried out on the F in Nice, that was 3 years ago and it's been fine ever since. The F was running very hot climbing the Alps last year but that was a combination of being low on oil and the radiator missing 30% of it's fins.
Allow twice as long as you think you need, consider an overnight stop, get the roof down as often as you can and enjoy.
How did you fix the pipe?
Next steps get the ferry/tunnel booked and some hotels for the trip in the summer.