I'm only 75 km to the south of you also just off the A50. Maybe we can make an appointment for you to come over and chat about the best course of action? I certainly can't help with doing anything myself I'm afraid, but can give some worthwhile advice I think. Email me? d.bytheway@gmail.com.
Pool of fluid under the car could have been airco condensation water-drain of course. Also don't forget that a filled expansion tank is not up to the brim of the neck, but up to the MAX mark you can see if you look way down into the reservoir from the neck. You may have been overfilling, which will all get thrown out.
Your coolant leak, if indeed there is one, may be the intake. Several, including me, have had that problem; we will see.
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