Best place to stay in Istanbul -SulanAhmet (£25 to 40 per night).

Low cost airlines go to Sabiha Gokcen Airport. Take Bus upto Taksem (cost 10 Turkish Liras). The journey is 45 mins to 75 minutes. From Taksem, take a taxi to Sultan Ahment. Better if you fix the rate before hand to 10 to 15 Turkish Liras.

Places to visit:

SultanAhmet mosque (blue mosque), Yerebatan Cistern, Top-Kapi Palace, museum opposite to SultanAhmet mosque if you realy interested in musuem.

Istanbul Nightlife: Taksem.

Turkish Hamam: Sultanahmet hamam at Sultanahmet. Approx cost Liras 60. The hama is not relaxing; you would need good sleep after you are massaged!