I think in your shoes I would be concerned/aware of the fact that it may be very, very difficult to find a job now in schools because of your circumstances.
I have a friend in similar position (although she only took 4 years at home) and she has been applying for jobs now for the past 4 years without success - even though she was previously graded as 'Outstanding'. She has been interviewed for dozens of jobs, gets great feedback, is consistently told 'you taught an outstanding lesson' - but in each case the job has gone to someone who has just completed their PGCE or, in one case last year she was interviewed in Feb for a post starting in Sept and it went to the girl who was basically 4 months into her training and who had (presumably) done about 8 weeks actual teaching. Her subject is also maths.
12 years teaching puts you (at least) at top of MPS - and having not done the job for 8 years you are, ridiculously, an unattractive proposition to most schools. Money appears to be everything - as does youth! All of the schools I know, and all my friend has applied to, are basically appointing NQTs who are much, much cheaper.
They are then appointing HoD at 26/27 years old - supposedly young and dynamic.
As a teacher of 40+ schools don't seem to want to know - you are expensive, lacking the latest 'up to date' ideas, not au fait with current Ofsted/data/AFL strategies, etc.
It's a bloody awful situation IMO - but I think you need to bear it in mind if you are considering going back into teaching. Nowadays if you've stepped off the career wheel in schools it can be almost impossible to get back on. There is massive unemployment in teaching currently.