At the PPL level, groundschool is not mandatory, although your school might want you to believe differently so they can retain a steady stream of income. But it's perfectly OK to self-study for your PPL and not attend any formal PPL groundschool whatsoever. (Having said that, some people are not good at self-study and really benefit from classroom groundschool. But if you're a Uni student it should be no problem whatsoever to acquire the theoretical knowledge by self-study.)
Also, the ANO does not specify any theoretical exam to be done before you fly your first solo. Most UK schools have a policy of requiring Air Law before first solo though, mostly to force you to study while you do your practical training. If you have a good enough reason (for instance because it's very likely you will not finish your PPL in time, and thus your Air Law exam would expire), the school can waive this requirement.
Furthermore, I'm with MDHAC. A gap year from University is likely going to decrease your employability rather than enhance it. Particularly if you spend maybe three months or more of that gap year to obtain a PPL, which has no commercial value whatsoever.