Before I replied to you, I did check the Porsche configurator to see whether Turbo S had a PSCB option in the UK, no. I also did a quick check with some UK Porsche forum members. So yea, your dealer doesn't seem to know his own product. Are you sure it was even a Taycan, or did you just trust the dealer?
As for traveling in the Taycan, I drove mine home from the dealer, 3500 miles across the US in the middle of winter (you can read more details on that trip
here if interested). No problems whatsoever. The thing which was slowing me down the most was traffic, not charging. On my last leg, which was in the slowest speed limit states, but least traffic encountered, I traveled 689 miles in 11h 13m, charging and meal brakes included - that's a 63mph average. I've gone across the US in a Model S as well, and is was very similar except Model S charged slower. With Taycan's 270KW charging, you can actually cover a lot of distance fast. I prefer to stop every 100-150 miles, which is ideal for fast charging as most of your charging will be close or above 200KW (in some parts of the trip I was somewhat limited by >150KW charger availability, but that is changing quickly).
In terms of range, an EV which can reliably do 200 miles in most winter weathers is all I need. If Porsche was to make the Taycan more efficient, I would opt for a smaller battery to reduce its weight (even better handling) rather than longer range. Also, Taycan range predictions, once it's had a change to train itself on your driving habits and weather, are MUCH closer than any of my Teslas ever gave. In a Tesla I always had to do an adjustment in my head of mileage remaining, the Taycan is pretty dead on (if I leave the house, travel 60 miles, the remaining range goes down ~60 miles) - I am still getting used to not having to derate the remaining range in my head. In a decade of driving Model S'es I never once hit the rated miles for more than a few continuous miles, so that ingrained in me to always derate the range I see.