If it was me I would take the tank back to the manufacturer (unless you made it yourself !!) and tell them to replace (not repair) in time for SVA.
If no joy - name and shame here.
If this is the second hole - there is a good chance there will be more in the future and as said SVA/MOT man won`t be happy with a temporary repair job.
Just my 2 yoyo cents worth.
