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Who advised you of this? How did they know it was the right side? Did you get the trouble codes pulled to indicate it? There are several topics about ABS troubleshooting in this 2nd generation 1996-2001 subforum, but something doesn't add up.
If you have 4WD, your front wheels' ABS sensor ring aka reluctor or tone ring, is inside the wheel hub. It is not user-replaceable. The ring itself doesn't/can't go "bad", like an external one could from excessive rust or road debris.
The best thing to do is hook up a scan tool capable of Ford-specific codes to see what the ABS trouble code is.
However, if you just want to throw parts at it... I've had ABS faults on both my 98's front wheels (one shortly after the other) due to the hubs wearing out. They seem to start throwing metal particles into the grease inside, that gets on the reluctor rings, before there was any other sign of them being bad (no excessive play or noise yet).
Replacement hubs (almost always) come with new ABS sensors. Where is "Newport"? If I knew you were in the US, I'd recommend getting a Timken hub (if that's what it needs) from Rock Auto, or a Centric if on a tight budget, but no low end/generic brands if you want it to last.
That stated, if you only need to TEMPORARILY pass the MOT, then what I would try is remove the old sensor (at which point it may break in two and leave the outer casing stuck in the hole in the hub so you may need a pick to get it out), use a chisel to flatten any rust on the top surface where the sensor sits to be sure it seats down in the hub low enough (trying not to get any debris down into the sensor hole if possible), and stick a paint brush or whatever down in there and clean the grease out of the teeth in the sensor ring, then install the new sensor. Frankly I wouldn't bother trying to clean it as you're going to need a new hub anyway, "IF" that is the problem, unless you really have to pass MOT ASAP.
Otherwise you can check for broken sensor wires, a fouled/corroded connector from the sensor pigtail to the ABS module, or could even have the ABS module itself failing. If the sensor is working properly, should be producing a low AC voltage pulse when the wheel spins. You can also measure the resistance of the sensor (unpluged from harness, wheel not spinning), should be roughly 420ohms, IIRC.