Many congrats on passing your test. Statistically, motorways are the safest roads. Most accidents happen in 30mph zones. However, as @kezo says, it all depends on your confidence levels. When my daughters passed their driving tests I paid for them both to have a one hour lesson on the motorway with their instructor. I would advise doing that if you are contemplating travelling 2 hours to then drive a brand new unfamiliar car home again.
In your situation I’d probably wait a tiny bit longer and order one locally, just to remove the worry. The fact that you are asking the question says to me that it’s a worry you could do without. Also, have you test driven one? It’s all very well her loving it, but if you are going to be driving it you need to be happy with it as well. There have been too many examples on this forum over the years of people ordering cars in haste and regretting it later.
Re your comment about prices. Nobody knows what will happen next week. If it follows the pattern of the last few years, some cars will be removed, some new ones may be added, many advance payment prices will increase but some others will fall. Overall, I suspect that the overall trajectory will be upwards, including EVs. If you are dead set on a specific car, the best bet is to say to the dealer that if you order the car this quarter (latest Monday) but the advance payment drops the next day, you want them to adjust the price on the Motability system to the lower price. It’s a 2 minute admin job and doesn’t affect the actual order itself. 90% of dealers will agree to this. If they don’t order from another dealer who will. It’s always better to do this than wait for the next quarter prices, as in the worst case scenario the car may be removed from the scheme and you can’t then order it at all. You are also protected from any price increase. Also, if you order and a better car appears next quarter you can always cancel and re-order. Good luck.