If your stay at BIG4 Mudgee Holiday Park includes a free afternoon, the region's wineries and national parks are the obvious draws, and both are close enough to make good use of the time.
Mudgee's wineries

Mudgee's wineries are a genuine drawcard, with a good number of cellar doors within a short drive of the park — worth planning around if wine is part of the reason you're here, and easy to fit into a single afternoon or spread across a full weekend depending on how many you want to visit.
Mudgee's national parks

If wineries aren't the focus, the region's national parks offer walking trails and natural scenery as an alternative — a reasonable way to spend a few hours without needing a car full of wine at the end of it.
For contractors or workers here for a regional project rather than a wine weekend, it's worth knowing a single cellar door visit doesn't need to be a whole-day commitment — many offer tastings that fit into a couple of hours if that's all the time you've got free.
Seasonal festivals run through the year in Mudgee, tied to the wine harvest and other regional celebrations — worth checking if your visit happens to line up, since it's more a matter of good timing than something to plan a trip specifically around.
For families here for a celebration or event, it's worth knowing several of the wineries also offer food alongside tastings, making a winery visit a reasonable lunch option as much as a wine-focused outing. [LINK: to the Food & Drink post's cellar-door dining section]
Planning a cellar door visit
None of this is essential if you're purely here for work — but if a gap does open up during a longer stay, Mudgee's wineries and national parks are both close and don't require extensive planning to make good use of.
The takeaway: Mudgee's wineries are worth the visit whether you've got an afternoon or a full weekend, with the national parks a reasonable alternative if wine isn't the focus.
If you're planning a cellar door lunch as part of a tasting day, it's worth checking whether you need a designated driver or want to arrange transport in advance — several of the better-known venues get busy on weekends, and having transport sorted ahead of time makes for a considerably more relaxed visit than trying to organise it on the day.