I've played one of the pads in Anything goes last year, think I was on clarinet, bass clarinet and tenor for that one. Can't remember any particularly tricky sections compared to other shows, or any horrible time signatures to contend with.
Ask for the pad in advance so you can have a look at the music and practice any bits that look a bit scary to you - you'll then have time to simplify (as Mandy has suggested) any passages which you think you can't handle.
When you get to the band call/tech rehearsal/dress rehearsal, there might be some cuts to mark in (if for example, there are any particularly complicated scene changes/set pieces that the director doesn't want to do...or a section that the cast can't sing very well...). You won't always get these in advance as some issues only become apparent on the dress rehearsal. I usually use small bits of post it notes to mark these as a) they stick out more than pencil markings in a dimly lit band pit, and b) they are easy to remove - you'll need to rub out any markings on the pad at the end of the run. Usually after the last show, the band will all remain in their chairs either frantically rubbing out their marking if they're organised...or sitting patiently to ask to borrow a rubber if they're not organised! Also - make sure you know how the MD is beating/counting the pieces, ie whether it's a fast four, or if they're beating two in a bar and note this at the beginning of the piece/section.
Go for it - if it's not your cup of tea you don't have to do pit work again, and if you do enjoy it, it may lead to further gigs.