First, download the stock ROM for your Galaxy Tab 10.1 P7500 XWKG9 European edition as-well-as ODIN (all links are at the bottom of this post). Extract the stock ROM on your computer and run Odin. Now, put you Galaxy Tab in download mode.
To do that, connect it to your computer and switch it off. Hold the power button and volume until you see 2 icons. Then, press the volume + button and it will then ask you “are you sure”. Press the Volume + button again one more time and you will able to put your Tab in download mode. Again the order of buttons is – power_ _volume -_ _volume+_
You will now see a yellow background on the first box of odin. This implies, you can now flash your galaxy tab. Click start on the ODIN and wait for sometime until it reboots. Now, we need to root it. Follow this Galaxy Tab 10.1 root (tc9.org) guide to root it.
Then, download Deodexed system files from here and extract them to your SDcard. You should now have done_app and done_frame folders on the root of your card. Install ADB (google for it) and run these commands:
adb shell su stop mount -o rw,remount -t ext3 /dev/block/mmcblk1p21 /system cp /sdcard/done_app/* /system/app/ cp /sdcard/done_frame/* /system/framework/ rm /system/app/*.odex rm /system/framework/*.odex mount -o ro,remount -t ext3 /dev/block/mmcblk1p21 /system reboot
Get back to recovery mode and enter wipe data/factory reset to reboot.