If he is non-salaried, what are his total earnings in the last 6 months? If he earned more than £9,300 in total, and this shows on his payslips, then you can still apply under Category A.
They will add up all the payslips, divide by 6 and multiply by 12. If this figure is more than £18,600, he will qualify under Category A and you don't need to worry about Category B.
If you are using Category B though, I would answer as follows:
(iii) Have you/your sponsor been in employment with the same employer and earning the amount specified in (xiv) below continuously for 6 months prior to the date of the application? (category A)
No(iv) If you answered no at (iii), have you/your sponsor been in other employment in the 12 months prior to the date of this application other than your or their current employment? (category B)
No - I have been with the same company for 10 years(v) What date did you/your sponsor commence your/their current employment?
Date he started working for employerSection 13 - Documents
Your relationship
Six items of correspondence addressed to you and your partner at the same address as
evidence that you have been living together since your last grant of leave in this category, or
from the date you first started living together up to a maximum of two years. See Note 11
Please give an explanation on a separate sheet if you cannot provide six items; if the items are
not addressed to both of you; or if they do not cover the 2-year period.
Being on a Fiancee Visa I haven't been working or paying any bills
Should I write an explanation on a separate page or its not applicable in my case since its my first leave to remain?
It is applicable to you, because it's one of the requirements of the FLR(M) application - they are expecting you to have lived together since you arrived on your fiance visa and to have proof of that (or an explanation as to why not).
So, you must either include all 6 documents, or explain why you cannot include them all.
Do you have your name on any bills yet?
What about a bank account?
Council tax?
NHS number?
Any letters from any official companies (phone, internet, etc.)?
You will need to provide mail for both of your FLR(M) applications and also your ILR application, so really you want to get your name on as many bills and letters as you can, as soon as possible after arriving in the UK on your fiance visa.
If you don't have 6 documents each yet, you can explain on the application that you have only recently arrived in the UK and don't have any/enough mail yet... then send anything you do have for both of you.