Firstly apologies as I know 4D scans have been done to death on here, but it's always been about, are they worth it or not.
What I want to know is. Where in London have you had them done and your experience? We've already decided to do it, we just want to now get the best value for money. With prices varying between £100 and £250 we just want to have this unique experience, without being disappointed or wondering if only we had only paid £30 more, IYSWIM.