Travel potty and spare clothes! Since potty training we've been away for the weekend a couple of times with LO, been to 2 weddings, aquarium etc. just leave extra time for travel in case you need to stop for a wee and have a travel potty
Yes we went out about 5 days in properly for the day (before we did odd local park trips) but the grouding we did at home while it was quiet! The biggest issue we had and still have is stopping something fun to potty - so we have to make the potty fun
We have a great little travel potty from John Lewis. I would stay in the house for the first few days and then venture out. It will all be too much for LO (and you!) to deal with potty training out and about and will probably cause a lot of stress and make the process even harder. When you do go out take 4 changes of clothes Good luck :)