notMrsR
CAB can't help you.
There are some helpful ex-pat forums.
This is what i think is true (am not expert):
Don't panic. ExPats fail-to-file tax returns a lot, It's very common.
I wouldn't bother with that form.
Get hold of the right forms for the right tax year (I guess you owe for 2012?) and file them soon. Your return isn't due until June 2013 and you can even request a deadline extension until September, I think. If your income in 2011 was over threshold you'll just have to file late taxes for that year too and any previous when you made lots of money; there will be some late penalties paying tax owed but not outrageous.
If you never owed taxes in previous years you don't have to worry about failing to pay tax installments last year; but you will have to worry about paying tax instalments for 2013 if you'll continue to have income over the threshold (because you were liable for tax last year, iyswim). That part I find tricky!
I would probably try the stupid Turbotax thing just because of the convenience of e-filing. I've had
experiences of bad advice from accountants so I would shy away from hiring one of them unless you think your situation is enormously complicated; I reckon I will pay less in penalties than I would to an accountant, and the accountant is never liable for any mistakes on your return, anyway. Technically you could sue accountant, but probably not worth it.
Your DS19 almost certainly does not have to file because he wouldn't owe anything, either (read upthread for details).
By the time you work thru allowances & deductions you may not owe for 2012, either. BUT if you can establish that now, then you will be in a good position whenever a year crops up that you do owe taxes, because you'll have paperwork to show you've been open & honest about previous income.