Head gasket on the way out, how long can I keep driving before getting it sorted?

Mr Rhode Island Red

My 2002 1.4 E11 Corolla has been drinking oil the last 2 months, and I've started to notice a milky buildup on the inside of the oil cap, the engine bay is pretty dirty as well near the base of the engine block on the right hand side, what's new this weekend I noticed there was a noticeable drop of oil on the tarmac when I moved the car after it being parked overnight.

The cam cover gasket was done less than 6 months ago so I'm putting it down to the head gasket being on the way out.

I do like the car so I plan on getting this fixed since the car is currently flawless apart from that, but I'm wondering how long I can safely continue to drive the car until then?

I normally only do short journeys (around an hour or so) but in 2 weeks I'll be visiting family and the car will have to run for about 5 hours with maybe one stop. A friend of mine told me that cars often go for a year or so with dodgy head gaskets and that once I keep an eye on overheating and keep it topped up with oil it should be fine for another while.

I just want to get a second opinion on this. Is it OK to do another 1000km or so before getting this sorted, since I might not get a chance to get it into a garage before then.

Also how much does a job like this normally cost? I've seen and heard all sorts of figures.

Edit: Car is driving 100% btw

martyc5674

I think your head gasket diagnosis may be wrong.
Best get it diagnosed first, no one on here will be able to answer your question without more info.