Wow, that's really exciting!!
My friend and I traveled in the UK and Ireland last August via rental car and hit a few of the places you mention but sadly we only had four days in Ireland
and didn't get to see nearly as much as we wanted.
If I recall correctly we rented through Hertz (I know we did in London but can't remember for sure if that's what we used in Ireland) using my AAA discount and travel insurance. Be aware that most insurance companies will cover your rental in every country in the world except Ireland!
For some reason they are concerned about driving safety in a country defined by one-lane roads, sheep around every corner and a reputation for alcoholic consumption.
Neither my AAA travel insurance nor my regular car insurance covered us there but I called and double-checked with the credit card company I was charging the rental to and it turned out their insurance policy did cover both Ireland and the Republic of Ireland. Unfortunately I had already made the reservation online and did not click "waive all coverage" at the time of reservation so that cc coverage was negated and I had to cough up for full insurance coverage through the rental company. $$$$$! They aren't kidding when they say rentals over there are an arm and a leg- be glad you're splitting it.
There were several places we considered for a pony trek including a company that basically lets you cross the entire country on horseback for two weeks with your bags being driven ahead of you to the next B&B, which we are SO doing next time!
We ended up doing a two hour coastal ride up in Donegal at Dunfanaghy Stables which was a very positive experience. I wasn't impressed with the horsemanship at the stable but the horses were pretty nice and they weren't deadened from plodding nose-to-tail down the trail day after day. They're used to walk/trot/canter on the beach or mountain roads for most of the ride and it was definitely faster paced if you are a more advanced rider. I'd recommend you stop in if you get a chance as the north Irish coast is amazing! We also picked up some great grooms caps and rain coats in Dunfanaghy. (The Giant's Causeway is also fairly close and worth a visit.)
After we got done in Dunfanaghy for the day we drove to a hostel in Sligo where we spent the night. The part we saw was a fairly industrial town but the hostel owner pointed us in the direction of our first Irish pubs where we went and had a glass of Guinness while we listened to the local musicians jam.
We sadly did not make it to Connemara as we wanted to but made some great new horsie friends across the country and ended our trip in Rosslare ferry port near Wexford where we departed for Wales. There are lots of forum members in Ireland so be sure to look some of them up! Many are south of Donegal and will be on your route down.
We were lucky enough to see a county fair with carriage driving classes and then stay with a horsie host family in Limerick our last night and I can tell you that local hosting is definitely the way to go if you can't afford B&B's. We really liked the hostels for cheap travel accomodations too but our biggest regret was zipping around so fast we never got to really explore any one location. We both said next time we're not going to try and hit two or three towns in one day as we travel but rather will schedule it so we arrive at a town one night, settle in, then spend the entire next day exploring and leave the next morning. It was so stressful the way we did it!
Do hit the Rock of Cashel if you get a chance, even our hosts agreed that while a major tourist attraction it was still very worth seeing and they were right. Haunting, amazing Celtic graveyard, hollowed-out cathedral where hundreds were burned alive by some authority or other, and then the Rock itself, a gigantic chunk of stone that was blown off the corner of one of the buildings during some epic windstorm.
This chunk of rock is bigger than two Clydesdales.
An amazing place and we would have liked to have spent a day exploring the town as well as it had dozens of fascinating little shops.
You'll have to tell us what you like best about southwest Ireland as we didn't get down there and that's where we plan to go next time.
Have fun!
Leia
We are spending 2 weeks in Ireland, flying into Dublin, renting a car, heading up to Donegal to spend a few days, then working our way down thru Sligo, Connemara, Clare, Dingle, and then Shannon to fly home.
