None of the aircraft are on the english register, there either the sunwings aircraft which are on the Canadian register, or Vikings planes which are on the Sweedish register so follow there own aviation laws.
Which base are you flying out of?
I strongly suggest you either book the seats if it means that much to you, or turn up at the airport early and be the first at check in! Refusing to take your seats or asking the crew to swap people around can cause a lot of discomfort and friction in the cabin, and on top of that there isnt a huge amount of time allocated to boarding and it could end up delaying the flight!
As for nerves, Doctors now can give tablets to help settle nerves, but It doesnt hurt to let your crew know, they can keep an eye on him and make him feel more relaxed and reassured!
