Surrinder Singh route

Since you are traveling on an Irish passport outside of Ireland and do not have a UK passport, then you can definitely be considered Irish if you want. The McCarthy ruling has nothing to do with you at this point.

You are also British and could get a UK passport if you wanted.

So long as you have been working in the Netherlands, then you could return to the UK on the basis of your UK citizenship (Singh judgement). You can also go on the basis of your Irish citizenship.

If you were planning to work when you arrive in the UK, then it makes no difference which citizenship you use. (Irish might be easier because you do not have to offer proof of work in the Netherlands and would not have to get a UK passport).

If you plan to not work, then entering on the UK (via Mr. Singh) might be preferable.