Just as an update I did this on my Used Approved Skoda Superb. I took the £99 deal (only available with PCP) which included 2 years warranty/servicing/mot/roadside. It was clear in the paperwork that as long as I withdrew/settled in the first 14 days all I'd pay was £5 interest per day. I got the car on Tuesday and withdraw today (Friday) at an additional cost of £20. I checked in the dealership first and they confirmed no problems with this. Interestingly all the benefits are logged against the car on the Skoda system. You get a separate "voucher" for the two MOT tests. The servicing is shown in the Finance portal. The warranty/roadside are logged on the system as well. I think you'll only pay an increased amount IF you wait until after 14 days at which point I think you can be charged an additional admin/interest charge.