You should consider external insulation IMO.
Its benefits are well-covered on the Construct Ireland Website.
I think Durkan EcoFix offer a free assesment and estimate, but there are others.
ONQ.
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All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.