Hi Amaria
Sorry to hear about the loss of your husband. Presumably you wish to secure the houses in Ireland and the UK for the benefit of yourself and your son. Gathering paperwork is part of the process.
Here are some questions that you will need to answer:
Did your husband make a will?
Do you have your marriage certificate?
Do you have a death certificate for your husband?
Do you have your husbands personal files? Passport? Tax return records? Bank statements? Pension statements?
In terms of the house in Ireland, the best place to start is with the firm of solicitors that you and your husband used when it was being purchased. They would be best placed in terms of advising you on the next steps, with regards to the house, and other assets that may form part of your husband's estate.
btw, just to clarify, was your son born in Ireland?