We were all in your position once ;) (unless you were born and raised here)we all had to start from scratch!the heat; yeah its intense but you will become used to it in no time! as for socialising; you just find your way! i came here only knowing me mum and dad lol...thanks to work and also getting a part time job in a pub here :P i met LOADS of people! (you can take the girl outta london but cant take london outta the girl! lol!
Look at it this way, you know you can plan a day at the beach the night before and it wont piss down with rain like it may do back home :D

Good luck mate and welcome to Doha! you're gonna be just fine ;)

Tomorrow is another day ;)