Your accommodation evidence is:
- Land Registry document
- latest mortgage statement
Your relationship evidence is:
- the 6 to 12 items of correspondence sent to the two of you at the same address
- your legal marriage certificate
You do not need messages between you, photos of the two of you, etc.
For the correspondence, the items you've chosen seem to all be bank, plus one council tax. But you have other things to choose from, so just to be sure you've got the variety of sources, see if you can get a NHS letter in there, or something.
I'm not confident about the solicitor letter, but if nothing else fits, use it. They're really looking for utility bills, council letters/statements, NHS, government agencies (DVLA, DWP, etc.)... official sources.