Hi,
We are Irish citizens and had an investment property in the UK, now sold. We did our tax returns in the UK ourselves, even though I was very nervous doing it to begin with. We found the relevant tax authorities in the UK very helpful and when we made a mistake (minor) they contacted us to advise us on the correct way to complete the forms. I don't see any problem in completing the UK tax returns yourself, but not sure about the Irish revenue.
If we were to own an investment property in the UK again, we would continue to do the returns ourselves.
Hope this helps.