Nats and Non-Nats units
I completely agree with visiting a NATS and Non-NATS unit. I was lucky enough to get myself into a small, tower only, airfield with about 3 movements a day. It seemed to impress the interviewers quite a lot. If you visit an airfield outside Controlled airspace (there are quite a lot of small ones), then you will find the interviewers know less about them and so won't ask you as many awkward questions.