You will also have to retake your driving tests, so you need to prepare for these also.
I don't know how long ago you took your test(s) so you may not have done some of the more modern tests, and you might need to get driving lessons and books etc to prepare.
You will lose money selling and buying another car.
Yes the insurance may be higher, but as you have had your car for a while and find it reliable, there is no guarantee a different older and smaller car will be as reliable, and could cost you money in maintenance that you might save on insurance.
You should also consider passing your tests as the first goal and not buying a new car until you have done this.
Also consider not driving for the next year to wait for the insurance to get cheaper. Have a look online to see if it changes price much.
HTH
Sparky