Separation and DIY Divorce

I live in Scotland. My wife and I separated just under a year ago and we are now filling in the form for a DIY divorce, ready to be sent to the Sheriff''s Court once the year is up.
We own two properties - one was the matrimonial home, one is a rental flat which is on the market and should be sold soon. I live in the matrimonial home.My wife lives and works abroad, but is still on the electoral role for the joint home, and is still registered for Council Tax etc.
We have agreed on the financial arrangements for after the divorce, and feel we should get the terms down on paper - I feel the Sheriff will want to see that.
Do we need to go to a solicitor for this agreement to be drawn up? Is this what is called a ''Separation Agreement''? Can we draw it up ourselves and sign it in order to avoid solicitor''s fees? I have heard that any signed papers are recognised as ''legal'', but maybe the Sheriff needs something more substantial?
Also, as my wife is still ''registered'' at the main home, will the Sheriff see a problem and delay the process? She is going to put her parent''s address on the form as her place of residence - she is now using this for post etc. Her foreign address is unreliable and not trustworthy for mail to be sent to.
I have read about ''Decree Nisi'' and ''Absolute''. What is all of this? I heard that the DIY process only takes a couple of months - will that be the end of it? Or do I still need to get the ''Absolute''?

Lots of questions! But any help appreciated!!

Thanks!

There is only one divorce decree in Scotland, so forget about Nisi and Absolute. The finances are sorted out before the divorce. IF you can agree the financial arrangement between yourselves it''s worth paying a solicitor to draft a Separation Agreement to ensure there are no problems in the future. Whatever happens don''t divorce until the finances are finalised.

As long as there are no children or outstanding financial issues one of you can then apply for divorce using the simplified procedure and serve the papers on the other. They will need to sign and return the document to the court so you need to bear that in mind.

Thanks Fiona. Really helpful!