
The biggest problem is not having a single point for collection. There are two areas, one for the in store items and the other for the yard stuff. Hard to fix given the layout of the store and the yard but an email telling you what to do would help a lot. Just give shop items a code of shp or yard items a code of yrd in the system and if an online order contains both of these tell the customer where to go, if the order only contains one code just set your email template up to direct them to the right area.
When you arrive a simple QR code scanner at the gate (with the QR code from the app or email) would open the barrier and alert staff that you are here and to go get the order. Take it one step further and use ANPR to read your reg when you arrive so they can find you or you collect a tag at the barrier similar to the McDonalds table service tags that use RFID to locate you in the store. That is getting fancy but at a minimum punch in your number at the barrier when you arrive.