Hi there. Yes there are plenty of children age 12 and around that age who are home schooled. Of course Tanglin (or any school) would be expected to say that homescooling is not the route to take, after all they have to justify their fees!
Here is my advice if you care to take some of i,t all of it, or none of it
Come to Singapore in August. Having the family so disjointed for 6 months will be more detrimental than if she did no schooling at all.
Go to the school she is at now and see if you can get a copy of the syllabus for term 1 Year 8 (the term that takes her from Sept-09- Jan10). They should be able to provide you with the whole of the year which will be even better. If for whatever reason they won't then you can purchase it off of the net. It will include learning outcomes, topics covered, and a book/textbook list.
As for "are 2 hours per day enough", then yes full concentrated study broken into 3x40mins sessions will in fact be more study than is done in most classrooms in an
International School. Many homeschoolers find that 1 year takes infact 1 term when home studied.
As for socialisation, its a misnomer to believe that this only happens in school. Infact the odds are more against you in school as you only have a set number of children to mix with. From our experience my daughter makes friends firstly with the Singaporean kids at our
condo who take the morning shift at school so are home by 1pm (local schools here either have morning or afternoon sittings). Secondly she has all the friends at various enrichment classes she does - fencing, iceskating, gymnastics, softball,art etc. Thirdly she has friends with other homeschoolers (and there are SO many!). They meetup regularly for study sessions but also trips to the museum, zoo, botanical gardens, Sentosa. Then there are the friends she mixes with at our condo after they have finished their international school day. Finally just sometimes she likes to spend time with her Mum Dad and baby sister
I first started home schooling because like you I was on a waiting list. Once I looked further into it and also tried a couple of schools inbetween there was just no going back and now home schooling is definitely the way forward for our family as we like to travel a lot.
From an academic basis kids in the UK and the USA do much better on average when home schooled. My daughter is able to be on Grade 2 reading and writing but Grade 4 in Math, she can add Spanish "just because I'm interested to try it".
Anyway, as you are looking for just a 6 month space, homeschooling will also enable you and her to spend more time together whilst you find your feet in Singapore - you can do it together