switching from marriage visa to tier 1--in country applic.?

Hello,

This question touches both on marriage visa and tier 1 issues, so I thought I'd post it here...

I've been married to a British citizen for a number of years but have only quite recently gotten a marriage visa (for the probationary 2 year period). having had work permits before. Unfortunately, we've been having quite a few problems lately and although it hasn't yet come to separation/break down of the relationship (as we're still trying to work it out), I'm rather concerned about what will happen if the marriage ends.

I should have no difficulty getting a Tier 1 visa in terms of points, but the issue is whether I would need to leave the country and apply from abroad, if the marriage breaks down. The Tier 1 section of the BA website says:

"If you are in the United Kingdom and wish to stay as a highly skilled worker, you will need to be sure that you can switch into this category.
Switching into this category is allowed if you currently hold leave in the following categories:
Highly Skilled Migrant Programme (HSMP)
Innovator
Fresh Talent: Working in Scotland Scheme
International Graduates Scheme (or Science and Engineering Graduates Scheme)
Postgraduate Doctor or Dentist
Student (under the Immigration Rules in force until March 2009)
Student Nurse
Student Re-sitting an Examination
Student Writing Up a Thesis;
Work Permit Holder
Businessperson
Self-Employed Lawyer
Writer, Composer or Artist
any other Tier 1 category
any Tier 2 category
any Tier 4 category
dependent partner of a Tier 4 migrant"

It seems that my particular circumstances as someone on a probationary marriage visa that doesn't convert into ILR, are not catered for. I'd appreciate if you could clarify this for me:

1. Will I be able to apply in country?

2. Do the BA staff have any discretion to allow an in country application if I am not in one of the above categories?

3. If I do have to leave and apply from outside, how long is the wait usually?

I'm worried about this particular issue as I cannot leave my work for more than about 20 days, in order to sort out the immigration issues from outside the country.

Many thanks for your help