It depends on the nature of the head gasket failure as to what the symptoms are, it would be very unusual for the head gasket to have cracked of warped in a way that would allow oil out of the block/head sandwich, but not let oil or water to mix or either of those into the cylinders. but not impossible.
Replacing the head gasket is a big job, not least because it involves.
Removing air intake assembly,
Removing exhaust assembly,
draining all the oil,
draining all the water,
removing rocket covers,
removing timing belt,
removing engine head (complete with all spark plugs and valves)
Then replacing head gasket (the part is surprisingly cheap).
then replacing the timing belt.
(and it makes good sense to replace the water pump at the same time and check condition of idle pulley bearings and tensioners etc)
replacing the stretch bolts that hold the head on (and tightening them to the specific torque, (which may require a torque wrench and an angle gauge after that.
refitting the timing belt can require specialist tools to lock the engine in place, then belt tensioning tools etc...
new oil, oil filters and new coolant...
parts and labour charges mean that it costs around £500 where I am.
In other news, I'm nearly catching up with your mileage too. 211,000 miles, so I expect to reach the quarter million miles in a couple of years...
My dads car has done somewhere around a half million miles now and it's still going fairly strong.