I've flown the LLR many times (I also live under it) and have usually been talking to LPL at the time, finding them very helpful. There's not nearly as much traffic as you'd think, but some of it (micro and ultralight) does not always show on their radar and a very good lookout is needed. Some of the traffic is also very interesting, having seen Spitfires, a P47 and the Catalina at various times in flight. 4km vis may be the legal minimum, but I wouldn't even consider less than 12km, especially as there may be something a lot faster than you coming in the opposite direction. It's also very bumpy with winds above 12 knots or when very hot, so a higher, northern route may be better if you have passengers who are worried by turbulence. (The same goes for the Menai Straits weekdays, when Valley keep you below 1500').