Sizing a battery bank for a small off-grid cabin in Scotland — where do I start?

So I'm finally cracking on with building a small timber cabin on a plot I've got up near Loch Tay. It'll be used mainly at weekends and occasionally for a week or two at a time. Not trying to run a full house off it — just lights, phone/laptop charging, a 12V compressor fridge, and maybe a small inverter for a drill or kettle occasionally. I've been lurking on here for a while but this is my first proper project and I'm a bit lost on where to begin with the battery sizing.

From what I've read I'm thinking somewhere around 200–400Ah of lithium (LiFePO4) at 12V, paired with a couple of 200W panels on the roof. The Scotland factor is what's scaring me a bit — I know usable solar hours up there in November/December are pretty grim, maybe 1–2 hours peak at best. Wondering whether I need to factor in a backup like a small wind turbine or a petrol genny for the darker months rather than just massively over-speccing the battery bank.

Has anyone here actually done something similar in Scotland or the north of England? Would love to know what your real-world consumption worked out at and whether you went with a single large battery or multiple smaller ones. Also curious whether anyone's running Victron kit up there and how it's coping with the cold — I've heard LiFePO4 can get fussy below about 0°C when it comes to charging.

@EwanPowell92 Scotland's winters will absolutely batter your solar yield — I learned this the hard way in my motorhome doing a February run through the Cairngorms. The sun barely crests the horizon some days.

A few things that shifted my thinking:

• Don't size for summer — size for your worst-case winter weekend
• Lithium (I use Fogstar Drift cells) genuinely transforms the maths because you can actually use 80-90% of capacity vs ~50% with lead-acid
• Victron's MPPT calculator is worth an afternoon of your time

For a Scottish cabin seeing genuine winter use, I'd be thinking minimum 10kWh usable before I felt comfortable, paired with a small generator backup for the inevitable week-long grey spells.

What's your load list looking like? That's honestly where I'd start before touching any battery sizing numbers.