By Toby Cudworth Gareth Southgate says England must be “very careful not to throw everything out the window” amid widespread calls for personnel changes against Slovakia. The Three Lions can book a quarter-final date with Switzerland should they emerge victorious in Gelsenkirchen, but the mood around England’s camp has been deflated after lacklustre displays in the group stage. England did win Group C ahead of Denmark, Slovenia and Serbia but won just one of their three games, scoring two goals. Southgate’s decision to start Trent Alexander-Arnold and then Conor Gallagher in midfield has been …