To make the dough, mix the flour and salt together in the bowl of a stand mixer. In a jug mix together the yeast, warm water, olive oil and caster sugar and set aside for 5 minutes. Start the stand mixer and add the liquid to the flour, mixing until combined and then leaving to knead for about 5 minutes. Place the dough in a greased bowl, cover, and set aside until doubled in size.
Once doubled in size, knock the dough back and flour your worktop. Roll the dough out into a rectangle about 45 x 40 cm. Turn the dough so that the long side is closest to you and spread the pizza sauce over the whole of the dough then place the sliced mozzarella on top. Roughly working in thirds, place the pepperoni on one third, the ham and pineapple on the middle third and the chopped peppers, olives and sweetcorn on the third third. Scatter the basil over all of the toppings and then working from the side closest to you, roll everything up, as you would a cinnamon roll. If the ends are a bit scraggy, chop them off to neaten and then cut each third into three pieces.
Grease a 20 x 20 cm square dish and place the pizza rolls into it - a line of pepperoni, line of ham and pineapple and a line of vegetarian.
Leave to rise for 30 minutes, covered.
Pre-heat the oven to 220 C / 200 C fan and when the pizza rolls have risen drizzle with a little olive oil and place into the oven for 50 minutes - 1 hour until cooked through and golden - you may need to cover with tin foil half way through to stop the top from getting too dark.
Remove from the oven and leave to cool in the dish for 5 minutes then serve and eat straight away.