Mix the flour, sugar, salt & yeast in a bowl. Make a well in the centre of the flour & tip in half the milk. Stir it in gradually, then add more (you may not need all the milk) to make a non-sticky dough. Turn the dough out onto a floured surface & knead for a good 5-10 mins until the dough is smooth. Shape into a ball, score a cross in the top, cover with a cloth & allow to prove for about 20 mins. In the meantime, put a large pan of water on to boil & preheat the oven to 200C & grease a baking tray. Once the dough has risen a little bit, shape the dough into bagels. (The dough will rise up to double during cooking.) 1 or 2 at a time, submerge the bagels into the boiling water for about 30 seconds, remove, shake off excess water & cook all in the oven for about 20 mins.