Thanks all for the useful comments & advice.

@contrails - Yes, I will have to top-up the school fees, but will still be saving more in Doha despite that.

@LincolnPirate - I think it will be a 4-year contract. I should be able to fairly easily get work back home when I return.

@simeen_maajid' - Hospital doctor.

@Mandilulur - £4.5k/month take-home in UK -> ~£10k tax-free in Doha. What I'm spending now on rent is the same as what I would spend on school fees.