Hello,

I'm thinking of replacing my door and bonnet hinges on my defender 90 td5 56 plate.

Any advice or tips before I do this job?

Easy job.
Door-hinge screws could be rusted into the captive nuts in the bulkhead so worth seeing if they turn before you start but other than that nothing to worry about. On assembly make sure you use plenty of anti-seize on the threads, will pay dividends in the future (my personal preference is a splodge of Waxoyl).

I take it you will be using SS fixings on reassembly?
What type of hinges are you replacing with, OE or something like Optimill?

It the existing screws are rusted into the captive nuts, a PZ4 screw bit in s 3/8 drive ratchet will either shift it, or shear the screw head - sorted either way. Buy replacement captive nuts and associated screws before starting. If the screw head rounds off, be prepared to drill it off. And as above, plenty of antisieze on the new captive nuts. I took the opportunity to spray lots of anti rust into the holes while the hinges were off, to protect the bulkhead (a bit). The standard hinges like to rust, so a few layers of paint on them before you start is a good idea.