Sorry to reply without a full answer, but it’s not cheap.
On the XK it was a few hours labour as the rear ones are a pig to get out and also pipes from cooling and supercharger need removing. Plugs themselves you can get online for under £100 but will be more from jaguar.
Also, I’m not sure when they need replacing on your model, but on the XK it was 100k miles or 10 years; think on F-type lower, but not a frequent job unless there a problem.