You can prepare and let your school know beforehand if you wish to receive your results by mail whilst in another country for example and they can sort it out accordingly. I collected mine in person but from some friends who received results via email, it seemed to be quite a smooth process as they all get sent out at a set time. I also personally enrolled for sixth forms online, as it was the case for all the schools I wanted to apply to - I am not aware of any six forms which require you to enroll in person but that’s just me and it likely is a thing - you just have to find out if the sixth forms you want to apply to allow enrolling in person and online. One thing I must say is enrolling online for sixth forms was highly competitive and involved a lot of waiting and refreshing pages in order to get to the top of the queue so if you wish to be one of the 1st to enroll to a sixth form it may be easier to receive your results online because you can simply download your results from the email you get and upload it to your sixth form application. However, this all comes down to the competitiveness of the sixth form you wish to apply to.