Somehow missed the notification of new replies to this thread.
Just a follow-up to what I posted before really.
About 10 days after being put on the priority list I got a text with an appontment for 4.10 on March 31st. As I work evenings this really didn't suit as I'd have to take 3 hours holidays to make it, and my holidays are worth more to me than that. I was on my way to work at the time so I decided to ring them the next day to try get a more suitable time.
Then stumbled across a thread on boards that same night, and there was a number of people saying to check the online system for bookings just after 8am (no chance) and after 11.30pm so thought I'd give it a shot. Have rescheduled for 25th March at 12pm - MUCH better for me and a bare 2 week wait. Apparently all the appontments for cancellations and rescheduling are updated at those 2 times of the day. It may or may not be fact, but it definitely worked for me anyway.
Just have to hope that if I get stopped in the meantime I won't get a Garda in bad form and they'll see that I've at least been trying to get the situation sorted as I can't really leave the car on the drive for another week when I've a 70 mile daily work commute.