Hi,
We relocated to UK from NZ late August last year.
We were able to apply to local councils for places without a postcode, from memory, with proof of right to residency. (I could be wrong on that one, it's all a bit of a blur! I'll check with the other half). We were offered places at a number of schools - some only had room for one of our daughters. We have two, they were aged 13 and 15, and went into year 8 and year 10. The UK school year starts in September.
If your son is going straight into GCSE's, into the exam year, the stress on him is going to be enormous. He is going to be adjusting to a new country, new culture, new school, having lost his mates, having to try and make new mates, dealing with what (we found anyway) to be a very different curriculum. Some stuff our girls were ahead on, but some stuff hadn't yet been covered in NZ, and then there's subjects which they had no background in at all - Religious Ethics, and History for example. My daughter, going into year 10, is doing her mocks this year, and we're thanking the stars that she has this year to adjust, and deal with all this, rather than be staring down the barrel of her GCSE's. We have engaged tutors for them, for maths, and for my eldest for all the sciences as well. Not cheap. Cheaper than private though!
My husband is in IT - his job is why we were relocated. We are living in the Reading area. It is increasingly perceived as a reasonable commute by train to London (45ish minutes), has some good schools, and is cheaper than London. . .