Anton, similar topics have been discussed/dealed with in QL for a while now.

I would suggest to start doing the following reading

http://www.qatarliving.com/answers/cost-of-living/how-much-should-i-expe...

And from there to do a search and read to some more recent comments/questions/suggestions or simply follow the link and get an idea from your own perspective

http://www.qatarliving.com/search?cx=008937172676595728955%3A066rihafv68...

Regards!!