If you go to Scrub you won't need to go to Trellis as Scrub has a shop.

At Marina you can easily dinghy to Scrub for some provisions OR jump on the Scrub/Marina/Trellis shuttle and do the shopping/lunch/drinks at Trellis.

We haven't stayed at Trellis since the Last Resort (or whatever followed) was there but we'd really liked that. When we've stopped in though we really liked the stores like Aragorn's and the little breakfast place that may not be re-opened. Always wanted to try Da Loose Mongoose but other than an early morning bathroom stop have really been there.