Crank sensor

I have a Gen 1 Coupe and recently experiencing a little problem.. when car starts from cold, no problem. After a run and the engine has heated up, stop the car go to the shops etc, when come back car is reluctant to start, it is definately ticking over just not catching the spark. Keep turning it over a few times them - hey presto it starts again. i've been told this sounds like the crank crank shaft sensor and I just want to be sure before heading out and buying parts etc.
Anyone else experienced a similar problem? I so I would like to hear from you asap as car is now for sale due to expanding family....