I have a 2003 C3, (1.4 16v Petrol) first issue is O/S headlight (dipped beam) failed, replaced the bulb (eventually!!!!

Driving today, temp gauge hit the top, followed by warning beep, stopped checked coolant level, OK, got back in started up again, and temp back down to three bars, shortly followed by max bars and warning beep, back down, back up, back down again, before it chose to fail to illuminate for a few miles, came back on missing a bar (5th one?) so there was a gap between number 4 and 6.....??
Climate control panel, works when it wants to, suspecting a lose connection? give the console a light tap and it illuminates and turns on, before turning itself off along with the illumination? Very erratic, leave it off for a while, press AUTO and on it comes sometimes lasts the journey, sometimes it'll last until the next mile marker, or it turns off when I glance at it?
I welcome any suggestions please! Also, what is the best code reader to buy, on a budget but will stop me buying bulbs and fuses that aren't required!
TIA, Boo.