I have just realised that you got your car at Williams in Bristol -- just a small bit of advice --- Bristol - Fishguard ferry to Rosslare and up the N11, M50 and M1 would be a helluva lot easier, and I think, definitely quicker than up the UK. Added benefit is that I live just 20 miles from Rosslare so there is a handy pitstop or overnight if going the other way for a service in Williams(Hint!)
Robbie - I'm sure we'll take a wee run round the country at some point. When I do, I'll message you and hopefully meet up. I looked at coming across various routes but once I'm into Belfast port I'm literally 10 miles from home etc. I've used a few of the southern routes on the bike over the years but not recently.
Hope your weather is better down there than it is here. We're grey'd out today with rain.