[Closed] Am I really looking at the best part of £1k to get a towbar and rack?

There’s a cut out pre marked on the bumper. It’s legit. Westfalia are VW OEM for towbars.

Bit more Googling and I see this is the case. Only the detachable Westfalia needs additional cuts too.

Is there an approved wiring kit? Do Westfalia make this too?

Yes, westfalia make the whole kit and caboodle: rear crash structure, wiring and the bar. VW rebadge it as their own, sometimes they don't even do that. If there's a bumper cut needed westfalia usually supply the template, glue and a removable hatch to hide it all away when detached.