As even selling off my vinyl hasn’t yet raised enough money to upgrade my 50D to a 5D Mark 3 and I don’t have any decent wide angle or Tilt and Shift lenses, I’m afraid I have nothing useful to contribute to this thread on matters photographic.
However the OP did mention that photographing castles was a main reason for the trip to Britain. I live in the south of the country of Wales (Wales being one of the several countries that make up the sovereign state of the United Kingdom) in a location between the towns of Monmouth and Abergavenny in the county of Monmouthshire that I believe to be the most heavily ‘castled’ area in Britain and, therefore, probably, the world. The following castles are all within a twenty five mile radius, exact distances from this location (Wernrheolydd) are given in miles in brackets with each listing:- Raglan (4), White Castle (4), Dingestow (5), Abergavenny (7 ), Monmouth (7), Usk (12), Grosmont (12), Crickhowell (14), Skenfrith (14), Kilpeck (16), Tretower (17), Chepstow (18), Caerphilly (20), Newport (20) Goodrich (22).
Most of the above are still in good condition and largely intact. I’ve probably forgotten one or two. This website gives more details http://www.castlewales.com/home.html
Enjoy your trip Creek28 and I hope you get lots of stunning images to take home!