If you never live in the property as an owner occupier then you are presumably liable for investor stamp duty on the purchase and CGT on any profit from the resale.
This is incorrect. If you are an owner occupier then you can sell any time and be exempt from CGT as long as the property was never rented out. The "five year rule" relates to the clawback of stamp duty where an owner occupier rents the property out (other than under the owner occupier rent a room scheme) within five years of purchase. See for a summary of the clawback rules. It seems to be a common misconception that owner occupiers are only exempt from CGT if they sell the property after five years of ownership. Of course if you buy a property and sell it on within a number of months without actually having taking occupancy then Revenue might deem this tax evasion or unacceptable avoidance.