By John Cross Kobbie Mainoo could be set for a dream full England debut at Wembley. England boss Gareth Southgate insists the 18-year-old Manchester United midfielder has proved he is ready to start against Belgium – and could even gatecrash the Euros squad this summer. Mainoo made his senior debut against Brazil as a late substitute on Saturday and Southgate says he will have no fears about putting in the teenager because of England’s mounting injury crisis. Southgate said: “Kobbie has a chance for tomorrow. He seems very calm. Definitely you can see he is taking everything in. Talking to him…