20th c deaths - you need buy certs from gen registry or possibly hope for a newspaper report - 1st is quicker but expensive - 2nd is very time consuming via microfilms at museum.
I don't know your travel arrangements but allow 90mins bus jouney from Douglas to Lezayre - the weather doesn't look as tho will be kind to you - last weekend gales (enough to stop boats) + more wind/rain forecast