I've just started an Early Expert XL campaign as the Irish.

It's proving interesting so far, and I love having access to Berserkers in the form of Gael Gaedhil. Celtic Warriors make an excellent Garrison troop thanks to 100 man unit size and they can be a very effective combat troop to boot. Add in Armoured Spearmen, a better option and any of the normally available Spears and you have the makings of a solid army structure.

As for a large shield wall, a few Kerns lined up behind them to rain Javelins on anyone who closes for Melee. And plenty of options for combat infantry in the form of Gallowglasses, Gael Gaedhil, Celtic Warriors and the more solid Fianna Eireann who are basically a souped up FMAA. Padding out your army with Celtics is a good way to get your numbers up and make sure you aren't outnumbered by the enemy. Keeps your troops morale up better that way.

One thing I did notice though was that troop production was very limited given you only have 1 province to train from and that's the same place you need to be producing Ships from and money is very limited.

I opted to take Northumbria first. Primarily because of it's trade value, but even aside from it's trade resources it has copper for mines and great farming opportunities. Basically it's cash cow that I need to milk very hard. I landed there with an army, and soon after, the English arrived to lift the siege. While outnumbered 2-1 I was able to thoroughly hammer them, kill their king and capture 600 prisoners inc. a prince. 6K ransom was just what I needed to finance reinforcements and develop the now completely looted Northumbria.

English offered me a princess for an alliance which I took greatfully as I didn't fancy fighting off their masses of troops backed with Royal knights. Numbers and attrition would ahve been a real problem, especially because I couldn't ship reinforcements in.

Had to build Fort, Port and Trader so had 10 turns with basically no income from it, but it's doing ok now so I have just got to hold onto peace long enough to get some more cash togetehr and build up the navy.