Thanks for your reply Clubman.
I tried about 10 times to reply to this post at home. I'm using NTL broadband. No problem with the site or the connection. Very frustrating!
Anyway...I think I've answered my own question somewhat. According to Bank Of Ireland's website...
"Variable Rate
A variable interest rate moves up and down to reflect changes in the financial market.
Changes in the rate do not affect what you pay each month, but rather how long will it take you to repay your loan. If the interest rate drops over the term of the loan, you will repay the loan sooner. If the rate increases, it may add an additional repayment or two."
So it seems that fluctuations in the interest rate will not affect my monthly payments...which is what I was worried about.