Dave

Your PVC door should be able to be lifted by about 5mm to 8mm by means of adjustment on the hinges via an alankey. With this house only being about 3yrs old the your floor will be whats known as a warmer floor, hence the concrete is laid on top off a 70 to 100mm polysytrene base( kingspan). This then makes the floor classed as a floating floor so you need to use flexible adhesive and flexi grout. The hump can be reduced with a scrabbler but you will still have to level because the format of tile you have chosen needs a very flat substrate to acheive the best results....Good luck......