Thanks for all your advice :o)
Do you think it would be more economically viable to take the car across to Ireland on ferry instead of flying over and renting a car?

"Do you think it would be more economically viable to take the car across to Ireland on ferry instead of flying over and renting a car?"
No.
You should visit DiscoverIreland.com as well for more tips. Many car rental companies also offer some great advice on navigating the narrow winding roads. Some of the highlights of my visit to Ireland were:
The Giants Causeway
Clear Island
Skellig Islands

I got a lovely call at 3 in the morning telling me that my friend in the UK had booked the flights! So its sorted!
There was a 3p special on or something of the like, so it worked out that a return flight from Luton to Dublin was 55 quid (around $135).
I'm now looking at landing in Dublin on Sat, heading straight to Belfast for the weekend and then working our way down the West coast, down and around to Cork, then Cork straight to Dublin for the Weekend then back to lovely Milton Keynes!
Thanks rainboy, I was looking at Skellig Island; Lovely! I wish the guy I was travelling with had a better budget to play with!
FYI, I looked into transferring money into his account for the flights:
Common wealth back charge AUD 28 and Western Union were charging AUD 22.
Cheers!