Head Gasket

Not sure of cost, but get at least two quotes and get it done asap otherwise it could cause extensive damage.
As for mileage, I`ve seen rovers come in with blown head gaskets with only 20k on the clock.

Although they are notorious for head gaskets MAKE SURE it is faulty by having a block test carried out . If it's just emulsified oil in the top end of engine and not in the sump , not losing coolant or over heating ,it MAY be just normal condensation .The Corsas for example are bad for this and you can pull dollops out through the filler cap and the gasket is o.k .It's not the head gasket on them though , just the set up on breathing etc . If used for short journeys and in this weather it gets a lot worse .

There is a modification kit for these where you remove the sump and fit an alloy brace and modified gasket and torq ,setting,main dealer should be able to supply.