Land Rover Repair: 99 Disco.......possible overheating problem?, coolant level, all terrain tires

Question
I just purchased a 99' Disco SD a few months ago from a used car dealership because my husband insisted.  He wanted a work car/play car when he returned from the middle east.  My father came with me to look at it and found some problems, which he said was minor.  He replaced the master cylinder, thermostat and the starter.  And two weeks ago, I got new All Terrain tires on it.

Last week, I drove it to the store which is about 6 miles from my house.  On the way back, I was halfway home and stuck in traffic the temperature gauge went all the way up.  It didn't hit the red zone yet, but I decided to turn on the heater and the gauge went down.  I turned off the heater when the needle was in the middle and drove 3 miles home and everything was okay.  I asked my dad about it, but he thinks everything is okay, but I want a second opinion.  Also I hear like a gurgling sound when I turned off the engine.  The coolant level is the same as it was before I drove it last.  Also, I don't drive with the A/C on.  Is everything ok or is it just in my head?

Answer
that sounds like an air bubble in the system, let it cool, and let it idle with the tank cap OFF for a while to allow all the air to work out of the system. Keep the watter topped up, do not rev the engine.  Putting the front up-hill will help, and run the heat full blast.