Istanbul is mysteriously ancient, while conveniently modern and a city that hosts millions of visitors yearly. According to the Istanbul Cultural and Tourism Directorate, 10,474,867 travellers came to visit in 2013 and it was described as being the most rapidly growing destination worldwide.
Weather wise, May through to October is the best period to visit. The Commemoration of Ataturk - Youth and Sports Day - is held on the 19th May and Republic Day is celebrated on the 29th October. Eid and Ramadan are acknowledged yearly, although the dates will vary according to the moon phases. The Prince Islands, are worth visiting too. It's a car free zone, and horse drawn carriages are the only form of transportation permitted.
British nationals need visas to enter Turkey, which can be arranged online. Make sure your passport is valid for up to 6 months from the date of your arrival in Turkey. It's also a good idea to get hepatitis A, tetanus, typhus and diphtheria vaccinations before travelling. London is 2 hours behind Turkey. Markets like the Grand Bazaar and Egyptian Bazaar are full of beautifully exotic goods, but be prepared to partake in the tradition of haggling to avoid being overcharged. There are plenty of fast food restaurants in Turkey and the food is considerably cheaper, although fish is expensive. Kebabs are around 8 TRY, while an assortment of snacks cost around 2 TRY and beer about 6 TRY.
Once you arrive in Istanbul, you can take the Metro M1 to Aksaray for about 4 TRY. The HAVATA shuttle bus runs every 30 minutes and travels to Taksim Square. Buses cost around 11 TRY, although no services run from 1am to 4am. A taxi to the centre will cost you around 60 TRY. Hostels and Guest Houses are very affordable, starting from 30 TRY upwards. You'll also find a wide range of accommodation in Eminonou, where the Blue Mosque and Grand Bazaar are situated, and Beyoglu, by Taksim Square and Istiklal Caddesi. The public transport network is well established and reliable, and includes the bus, minibus, metro, Metrobus and tram services. Access to all of these transportation modes is available with an Istanbulkart, or Istanbul Card. Taxis are more costly, although they are still comparatively cheaper than those in the UK.