Aug 2, 2014 - 5:50 PM
Yes, the pass will cover Lucerne to Grindelwald (most scenic) or Bern to Grindelwald for free. You can download the map from our pass page to see what's covered.
Buying in advance is the most convenient way. Although the price is the same online and in Switzerland, shipping to the UK is free, and you can pay in GBP so there's no costs due to exchange rates on the day of purchase. Also you can validate the pass yourself, so you'll save time as you can immediately board your first train. All you additionally need is a ticket to Bern or Lucerne, but you can get that quickly from ticketing machines in Zurich, or even online.
See here for points of sale.