from the sound of it, your getting your cars electrics and tow bar fitted, hence the question? if i was you i would be getting the 7 pin (12n and 12s) fitted, you can then use an adapter to change over to 13 pin if you need that,
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.