Gearbox oil level

the level won't affect it, incorrect oil type can cause this, as can a sticking clutch, to get round it just put it into first before starting the car (with the clutch down.

Won't be the oil type as it's been in there since new.... could be the clutch I guess but it doesn't creep forwards on level ground with the clutch all the way down in first gear. One thing I have noted recently (and TBH I can't recall whether it's always been like it) is that with the car in neutral and the engine idling there is an additional sound from up front that goes away the instant the clutch is depressed. Sounds like something is turning that's not balanced right and is more noticeable inside the car than if I stick my head out the window.

Thanks,

Peter.

With the clutch engaged the gearbox layshaft will be getting driven round by the engine so you will get a slightly different noise if you're listening out for it. If the noise is more noticeable inside the car it's probably just that some bit of interior trim or similar is happening to resonate with that slightly different vibration. If this were a brand-new S-Class then I would refuse to accept it until it had gone gone back to the factory to have every last grommet bunged with mastic putty, but it's a 2000 Fiesta, it's going to rattle a bit here and there.

If you can't remember whether it's always been like that it can't be that bad.

The noise could be gearbox input shaft or thrust race. Many cars make a slight noise as you describe. Replacing the clutch and thrust race on one of those is not a cheap, quick job, and the noise might still be there, however it would probably cure the gear selection issue.

That is perfectly normal.

Yup. you'll get noiser without creep if the clutch spigot bearings sticky though. It's one of those "If it ain't worth changing the clutch it ain't worth being worried about" issue though.