The health check I believe can be done without servicing. The warranty issue is the conundrum. Would £2700 cover the cost of all repairs that might be required. I mentioned to the dealer on service that I thought the rear camera was slower in engaging than my previous 2 Lexus. They decided that they would replace the hard drive. The part alone was £1800 and with fitting would have been closer to the £2000 mark. To me extending the warranty was worth the approx £83 a month for 11 months it will cost.
I have Gold membership so my Dealer gives me 15% discount on practically everything. To me it works, but to others it might not.