I have a 06 plate Focus Estate diesel. I have a knock/rattle that sounds as if it is coming from the bell house/ clutch area. Any suggestions as to what it may be?

Flywheel maybe? Does the noise change as you move the clutch?

Yes it does.

I'm thinking dmf too

Yeah almost certainly sounds like DMF if the noise changes when you move the clutch.

I had the same thing go on my MK1.5 1.8 TDCI Focus.

What are the consequences, actual and financial to getting it sorted?

I'm sure the prices vary considerably but my competent local brake and clutch centre quoted about £700.

A dmf dampens out low frequency vibration and reduces stress on the drive train created by high torque diesels so it makes them nice and quiet.

I was going to replace mine with a solid flywheel but then the noise disappeared and it didn't affect starting and that was 18 mnths or so ago...I don't do that many miles but every six months I have a look at the starter motor to check for metal swarf as this is an indication that the dmf is beginning to break up. The rattling will be a broken spring or two residing within the dmf, it sounds terrible at idle or low rpm so unless starting is being seriously affected I wouldn't be overly concerned if my experience is anything to go by.

Avoid pulling hard in a high gears and get it fixed in your own time.