My experience with Tesla is that the things they told me prior to order (verbally) we’re not true after I had taken delivery. They then refused to acknowledge their error and refused to rectify that error. Consequently, I do not trust Tesla, I do not believe anything they say.
What you are describing sounds like a bribe.
Other than pay a deposit, why would they ask you to pay them £100 to deliver a car in 6 weeks? This is a significant value vehicle purchase and your story sounds like the way fish is sold at Billingsgate Market. Give them £100? They must think you are mad (or gullible)