dunno if anyone has said this but before you disconnect the battery you should try depressurise the system buy starting the car with the fuel pump fuse removed...its the top one of the set closest to you by the battery (15 amp)
but still be careful when removing the hoses as they still squirt!! it burns pretty bad when it gets in you eye!!!!!
also once you have all the tank sealed and cover back on i would give it at least 5 mins before connecting the battery back up as there will be fuel vapor in your boot
my two cents anyway