Biometric card stole - looking for advice

[Kmike92]

Hello. As the title suggests, my biometrics card was recently stolen after my wallet was lifted from me in London. I've reported it as stolen but the information I received from the UK government has me panicked. According to the UK Visa office I need to reapply or face a potential fine, but the application process can take up to eight weeks.
I'm heading home (permanently) in four weeks. In order to fast track the process of getting a new card, I need to pay a few hundred pounds, which is unacceptable.
Basically, my question is do I need to apply at all if I'm not staying in the country? It seems like a massive waste of time and possibly money. Any help would be greatly appreciated.