Figured as much!

Thank you for your help. It is greatly appreciated.

Republic of Ireland is not in the UK so UK stamps will not work for your SASE.

You will need RoI stamps or to include some Euros.

http://www.anpost.ie/AnPost/ Should have the info that you need.

Or, how would I go about buying postage appropriate for the SASE to be sent from outside the UK?

Hi!

I want to request an autograph from an actor whose address is in the Republic of Ireland.

Naturally, I will be including a self addressed and stamped envelope. However, I am wondering about the stamps.
I have bought two 97p Europe stamps from the post office, complete with airmail stickers. One lot will be for the letter I am sending, the other for the SASE. Will there be any issue when it comes to getting that SASE returned? Will the UK stamp still be okay to use, even when being sent from somewhere outside the UK?

Any help would be much appreciated! I want to just make sure that this is okay.