There is a statistical probability that if you're an expat you'll be living in either Greater London, or the South East. That is simply because of the economy. It is the second largest regional economy in the UK (after London), and the second richest region per capita (again behind London). According to Wikipedia, if it was a country, it would be the 31st largest economy in the world.
It is also probably the most advanced in the UK. Certainly many hi-tech companies call it home, most notably around the M3 in Surrey and the M4 in Berkshire.
Perhaps as a result the South East is the most populous of the nine official regions of England with a total population of over eight and a half million living in Berkshire, Buckinghamshire, East Sussex, Hampshire, the Isle of Wight, Kent, Oxfordshire, Surrey and West Sussex. A significant chunk of the population live in seven cities: Brighton and Hove, Canterbury, Chichester, Oxford, Portsmouth, Southampton and Winchester. Other major settlements include Reading and Milton Keynes.
For those jetting in and out the SE is served by Gatwick Airport, the UK's second-busiest airport, and its coastline along the English Channel provides ferries to mainland Europe. Heathrow is also only a stones throw away just outside London. In England at least, you can't get more connected.
Top: The UK's second busiest airport, Gatwick; Second from top, Brighton Pier; Second from bottom, one of the world's best, Oxford university, Above: The iconic White Cliffs of Dover.
Despite the number of people, the region is known for its countryside, which includes the North Downs and the Chiltern Hills as well as two national parks: the New Forest and the South Downs. You can get out of the cities and breath. There is also not an insubstantial amount of coastline. Think Brighton, or the White Cliffs of Dover...
For academia and research, the region has many universities; the University of Oxford is ranked among the best in the world.
Getting in and out
Most main routes in the region are radials from London.
The main road transport routes are along the M1 through Buckinghamshire; the M40 through Buckinghamshire and Oxfordshire; the M4 through Berkshire and Buckinghamshire; the M2 motorway/A2 and M20 through Kent; the M23 through West Sussex; the M3 through Hampshire.
The main intercontinental airport is Gatwick Airport, with regional airports at Kent International Airport (Ramsgate), Shoreham Airport and Southampton Airport. Heathrow Airport is in Greater London but also serves (and is serviced by) the South East region.
The Great Western Main Line passes through Berkshire and southern Buckinghamshire.
The South Eastern Main Line and High Speed 1 pass through Kent; the latter connects to the Channel Tunnel. The Brighton Main Line passes through Surrey and West Sussex.
The North Downs Line runs from Berkshire then through Surrey to connect with Sussex and Kent.
The West Coast Main Line passes through northern Buckinghamshire.
The Chiltern Main Line is a major commuter line between Birmingham and London passing through central Buckinghamshire and Oxfordshire.
The Port of Dover and the port at Folkestone have many ferry services to France.
The greatest concentration of the most prestigious fee paying schools is in the South East. Think Bedales, Charterhouse, Downe House, Eton College, Frensham Heights, Hurtwood House, Lancing College, Roadean School, Sevenoaks School, Tonbridge School, Wellington College, Winchester College, Wycombe Abbey... are all in SE England. Links to full reviews below.
If you're living in the South East however you will want to consider the state school option. Buckinghamshire, Medway and Kent, and Slough have an almost completely selective education system. Kent has 33 grammar schools, Buckinghamshire 13, Medway 6 and Slough 4. In the top thirty schools at A level, it is almost exclusively selective schools; one or two are sixth form colleges.
At GCSE, the area in the South East (and England) with the highest results is consistently Buckinghamshire. Berkshire is split into unitary authorities, and Wokingham, Windsor and Slough have the next best GCSE results.
All of Berkshire's unitary authorities have results above the England average, with West Berkshire considerably above average.
Schools in Surrey and Hampshire also have consistently good GCSE results, and they are above average in Oxfordshire, West Sussex, Kent, Medway, and East Sussex.
There are a small number of districts where results are significantly below average including the unitary authorities of Portsmouth (one of the lowest LEAs in the country), the Isle of Wight, Southampton, Brighton, and the districts of Oxford in Oxfordshire, Adur in West Sussex and Hastings in East Sussex.
Sources: Considerable thanks to Wikipedia for the data found on this page.