Welcome to UKY!
Solid cohabitation evidence is more important (crucial) for unmarried partners. As you are married, there is no requirement to have previously lived together - and for most long distance couples, that's actually impossible until the visa is granted.
You will need evidence of your relationship - so your marriage certificate, a few photos, any evidence for the time you have been living together, communication records for times you weren't, and so on.
You will need evidence of accommodation, so you will need documented permission from the homeowner that you can reside there. This isn't to prove your relationship, but to prove you and your partner have available and adequate housing. It is a required component, and the application will not be successful without it.