Scotland in October / X100V / XT4+18mm and?

We typically visit Scotland once a year. I think the 18 will be wide enough. My preference for travel would be the 16-80mm F4, which is a sharp lens giving you a lot more versatility at lower weight than 3 primes, and is great on the X-T4. But I'm guessing that since you don't own any zooms you want to stick to primes!

On the drone front, buying something less than 250g in weight (e.g. the DJI Mini 3/3 Pro, or Autel Nano/Nano+) means you can fly in far more places in the UK. You do need UK CAA (Civil Aviation Authority) registration, but it's cheap and easy to do online.

October weather in Scotland is unpredictable, but tends to be wet and windy. Take appropriate wet weather gear, and a clear shower cap works well as a camera cover. It may significantly limit how much drone flying you will get to do -- you can't fly in the rain, and wind is a problem with <250g drones.

Edinburgh is very photogenic -- the old town, Castle, Holyrood House, Arthur's Seat are all worthwile. We've done a loop North-East out of Edinburgh via Dundee to Aberdeen, then into the Cairngorms to Ballater and then up to Glenlivet / Speyside, following the river to Aviemore. From there you can go West to Inverness / Loch Ness, down to the Trossachs, or back to Edinburgh.

For short day-trips from Ediniburgh, Rosslyn Chapel just outside Edinburgh is very interesting to visit and something you won't see anywhere else, though no photography inside. Sterling Castle is also picturesque. Lots of castles also along the coastline East of Edinburgh if you are into history.