Too late, I already know about it
I agree with you about the roads, not many pot holes but they are far from smooth, especially around the rural routes you'd have taken. The Antrim coast is stunning, I was up there 2 weeks ago when the sun was shining making the sea a beautiful blue, especially around the rope bridge which I presume you didn't visit while on the coast as you'd have mentioned it, pretty scary
As for the fuel, almost impossible to get in the south, but 97 is everywhere here, just no 99 You probably spent most of your time away from the cities and large towns so came across mainly local garages or the likes of Maxol etc which are pants, but every large town has a BP for your 97.
There are actually quite a few garages even in large town with dedicated red diesel pumps. No matter what town you're in, there are farmers pretty close and need to fill those old work horses somewhere.
I'm glad to hear you had a great time, except for the cats eye incident Wish i'd have known you were coming over I could have given you a few real hidden treasures on your route