Update.... Went to Chonburi immigration yesterday with my Non O 90 day application.
Forms required:-
1. TM86 change of visa
2. Certificate of income
3. Copies of all relevant pages of my passport
4. Rental agreement
5. Owners ID and house book (copies)
6. 2 x photos
7. Hand drawn map of directions from my condo to immigration office
8. Fee of 2000bt
I also took with me bank statements and pension information to support the application, but I was not asked to show them...
Signed copy of my certificate of income returned to me to use for my 12 month extension...
Informed to return on
*****
/18 to collect my passport containing new 90 day non-O visa (all being well).
Thanks all for the advice along the way!