I currently have a U first on the variable rate
does anyone know if there are any penalties for making extra payments to try bring down the repayment amount or mortgage length?
On any variable rate or tracker mortgage lenders can not refuse overpayments or charge any fees or penalties for overpayments - only fixed rate mortgages have prepayment penalties and only for the duration of the fixed rate period.
One piece of advice - make sure you make it clear that you want your overpayments to be taken off your outstanding capital balance with immediate effect. (Might seem obvious but Niall Brady had a story in the Sunday Tribune recently regarding a readre who had been making overpayments for years, but Permanent TSB didn't automatically apply them off his outstanding loan balance.)