Old shape KIA Picantos have been reliable, but you are right about the boot. I remember this vividly from the launch because we had to park some distance from the tow of San Giminiano and to make sure it didn't get nicked I had to hoik my bag with me.

Best bet for £3k is a Toyota Yaris 1.3, but it has to be original pre-2006 shape to get the four-speed torque converter auto. Later 2nd shape Yaris had bad automated manual transmissions.