I went to Flowerhill for a week in 2022 and loved it. Both had a blast and learned a ton. Two XC sessions a day (usually around 90 minutes each) plus an optional lunch hack with the working students, which I always did. I initially reached out directly to Oliver and he had me book through an agent he recommended.
I flew into Dublin, stayed in Loughrea, and rented a car to get around; it was about two hours Dublin to Loughrea and 30 minutes Loughrea to Flowerhill. (Loughrea was very walkable and I only used the car for the airport and Flowerhill runs.) My entire trip was solely to ride, so I took all my stuff (boots, britches, vest, and helmet), which was easy to do.
I think anyone from Starter/unrec through Training or so would have a blast there. If you were confirmed at Training, ready to move up, and explicitly wanted to jump big, it might be a bit basic for you, as they have a lot of smaller stuff; that said, they also vary the horses they give you to increase or decrease the challenge. I was very straightforward with them in the pre-booking forms that I’d only ridden through BE80 / US BN and so they started me on a very sweet, very round girl (who I still enjoyed very much!), but when we were out Oliver watched for a bit and then said, “Oh, you can actually ride”; subsequent to that Pony Spice Level increased commensurately going forward!
Horses were lovely and well-cared-for, and instruction (from both Oliver and others) was great. It was almost as though my very good regular coach had acquired an Irish accent and been transported across the pond; I have now been encouraged to SHORTEN MY REINS, SIT UP, AND PUT MY LEG ON in multiple countries. The main difference was that a) they let me jump bigger things than she would have and b) she couldn’t do anything about it but facepalm when I told her about it afterwards…