I was guessing somewhat - felt the need to be quick before the OP makes a terrible mistake. Mind you a quick check shows £150 is about standard unlocked price.
New best advice. Buy for £99.99 on 02 PAYG, throw away 02 SIM, put in Giffgaff SIM (runs on 02 network). Should work. If not a friendly...
Motorola Moto G, about £150 without contract (don't get a contract! - or at any rate get a SIM only one)
Great phone for substantially less than 200 notes, does everything you need. You are obviously not into gadgets so no need to pay a huge premium for the higher end stuff.
That said if you...