It might be a good idea to carry along a Digital Multimeter - so you can check your battery when the engine is running and see what the charging voltage floats to.
Then when you're done driving and getting ready to go in, try testing that voltage when the engines shut off - usually the ciggarette lighter (12 volt power port or whatever port) when you're inside the car - easier there - good way to monitor. Then recheck before your start - then monitor that voltage as you let the engine warm up.
When you chart this, you'll see the votlage will drop at rest, but starts out nealy full charge when you shut it off, but when you get back to the car the voltage will drop - it's normal - but what you got to look at is how far the voltage will drop as you start the motor (cranking voltage - much like your batteries CCA rating) can offer clues as to what is going on with your system.
The Alternator; one, the Check Engine light goes out - two, means the PCM and BCM (Engine and Body modules) are setting the charging voltage and the alternator should be filling up the battery. But if voltage is weak to a sensor in one subsystem - the WHOLE system seems ok, no matter where you check, except for that sensor - which if you see this but have issues with hesitation - it may mean you have weak power points to some sensors.
Or more of a physical Wear condition, your cam belt is aging and it's internal timing belt needs to be replaced. Possibly even the Water pump.
We don't see you service history on your vehicle - but it's a 2005 - so that means you deserve a congratulations - for not too many older vehicles in the UK make it past MOT issues this long.
You just might need a little TLC around the battery and power connections - even fuses - they are not infallible and are left in an environment similar to the engines all the time - so they are subjected to the heat, moisture - vibration - would not hurt to check and pull fuses to verify that their terminal connections are still working.
That's pitting on the lower portions of their legs,
Caused by corrosion - eventually causes intermittent
failures then it will literally plug up the terminals' socket
forcing you to tear apart the block and remove the debris.
I've had fuses in older SUV's that fell apart and left their "leg" at the terminal - corroded away - due to the environment and their age.
This also applies to the sensor grounding points - a long leg of a journey in the wiring harness might vibrate a wire loose off a ground lug, so be sure to look for and recheck - clean as necessary - those points you can get at.
