Cattery all the way here for that length of time.
Cat is anti-social/nervous, and won't engage with anyone other than us (so if a cat sitter came, the cat would steer well clear and wouldn't see anyone)
Cat LOVES the outside, and loves to bring presents in from outside. Daren't risk allowing the cat unfettered access to outside given that a cat sitter wouldn't see her, so wouldn't know if she was in/out/OK, or risk the poor cat sitter having to deal with mice in various states of completeness.
Cat HATES being shut in (and having to use a litter tray). Would have to shut her in for that length of time (due to points above), so this is pretty cruel.
Local cattery is run by a lovely lady who Cat will let talk to her/stroke her/play with her. Whilst she doesn't have completely free access to outside, she has space to roam/a run, so she can at least get some fresh air.
But the main point is that cattery will take total responsibility and deal with anything that arises. If the cat is ill/injured/needs medication - all taken care of. If something happens on the cat feeder's watch, then you'll have to deal with it all, remotely. Too stressful for everyone.