Thanks for all the good advice and comments.
Some further updates / corrections. The dealer didn't offer a test drive with space saver on, I may have worded that badly. They mentioned it was on and I said there wasn't much point until the replacement was done.
During some further discussions today, they inspected the tyre on the damaged rim and decided they would replace both front tires to match the rear, which I think are on Bridgestone Potenzas. I also found out that the car did about 1,500 Miles as a demo, before being sold on to someone who had it for nearly 2 ye