As it`s a bank holiday and you have nothing to do....
you might want to check the battery condition with a meter(or take to local tyre centre and get it checked). Look for nothing less than 10 volts and up to 13 on a good battery. Then, try disconnecting the leads on the battery, taking it out and giving it a really good slow charge. Twice in the past (on other cars) a failing battery has caused random stopping/cutting out.
An ECU reset as follows might be an idea as well:
To do a ECU reset the first thing you need to do is disconnect the battery (the negative terminal) for 1h, to clear the "adaptive memory" from data.
Then you reconnect the battery, turn the key to MAR for 90 sec., then
to stop, leave the key in and wait for 90 sec., then start the engine
without touching the throttle and let it run for at least 15 min, i usually let it run until the radiator fan starts, to set new idle speed values, turn off the engine and leave it for 10 min.
Then if you want set the ECU to some "sporty" values take the car
out and give it a full blast (rev it full on every gear and full throttle),
but be aware that this values gonna change as you drive over time and the ECU adapts to your driving stile.
Now, I only suggest this as it can all be done for free, but the crank sensor would seem to be the more obvious answer.