What should I do about a P0369 error code on a 1996 Jaguar Vanden Plas with 144000 miles.

Check electrical wiring first , as with the age of the car wiring are known to get dry and cause problems

Camshaft position sensor B bank 1 intermittent.

Intermittent could indicate faulty wiring or connectors somewhere between the sensor and ECU, though it could be the sensor. It is even possible that part of the ECU itself could be faulty.

The wiring is quite vulnerable to internal breaks where it is subject to heat and vibration.

You should not ignore any fault code but get it checked.

Replace Camshaft Position sensor Bank 1