If you're not sure on what area you want to go into, doing a full degree is your best bet. Most Unis have a common first year for engineering, which means you can apply for a general engineering course and then choose a specialism after you've done a year doing general courses and trying out different diceplines. I know for certain Warwick does this, and in sure other places to, but I'm not an engineering student do I couldn't help too much with specific institutions.
The problem with an apprenticeship is that they're so specific that you will definitely limit yourself to a small area of engineering, whereas a degree is going to be more general. Also if you're enjoying physics Alevel, a degree is going to be more theoretical than an apprenticeship, so you might enjoy that more
. Really unless you're desperate to start earning or really don't want the debt, uni is your best bet.