The nearest LIDL store is close to U-Bahn station Nollendorfplatz at around ten minutes by foot (according to Google Maps).
You can actually shortcut a little bit by going through Maienstraße and the inner courtyard of Berolina Bowling Lounge. This shortcut is not recommended if you're on your bicycle though.
One drawback of discount supermarkets such as LIDL is the relatively small variety of products. You will find there anything you want to find in a grocery store, but if you're looking for a special brand of coffee (e.g. Lavazza, Segafredo or Illy), LIDL may not have it but you will find it at EDEKA or REWE. Same thing with alcoholic beverages: the selection in beer, wine and liquour is limited.
Also, LIDL does not have a meat counter as they have it in every butcher shop or at EDEKA. You can still buy meat there, but it will rather look like this.