Disclaimer: This page details my personal DIY experience. I have no qualifications to do this work. If you carry out any DIY based on information on this page you do so at your own risk and I accept no responsibilty for any negative outcomes.
I needed to take the cylinder head off a ten year old late 70's Ford Fiesta. I had a Haynes manual and it said to undo the bolts fixing the head to the engine block and then lift off the head. It suggested that if it didn't come of straight away to 'tap with a wooden mallet'. After spending about an hours double, triple and quadruple checking I had undone all the bolts and whacking it as hard as I could with a large wooden mallet it was still very firmly stuck in place.
I had almost given up hope of getting the head off when I decided to try a different approach. I bolted the exhaust manifold back on to the cylinder head and jacked up the front of the car. I then placed a length of 4 by 2 timber between the ground (concrete driveway) and the exhaust manifold and slowly lowered the jack. Initially, I only jacked the car up a bit and the head gasket supported the weight of the car not supported by the wheels when the jack was lowered. Eventually, I jacked the car up so that both front wheels were off the ground and when I lowered the the jack, the head gasket split releasing the cylinder head from the engine block.