I just had the nuchal as the risk came back low (had quite a high risk result when I had the nuchal where I live in Sweden, so when over in UK for Christmas I booked myself in for a CVS at FMC). They re-did the nuchal (plus blood tests) and then because the risk was low I decided not to go for the CVS. They give you the risk result straightaway (to decide whether to continue to CVS) but obviously it takes longer for all results to come back from CVS.
The ultrasound equipment is so good at FMC and the doctors who perform the scans are excellent (and very nice!) so even if you didn't carry on to have the CVS (if they suggested there was no real need to) you could be pretty calm. They can check much more of the baby than normal ultrasounds. If you want a CVS the doctors are all very well trained (the receptionist laughed - nicely! - when I called panicking about chance of miscarriage and said I wasn't to worry for a second). If you want the main doctor (Nikolaides) then he sees people on Wednesday and you often have a very long wait. All the doctors are chosen and trained by him though so unless you're particularly nervous then you can be happy with one of them, I would have absolutely trusted mine.
Very helpful staff, lovely doctors and a fab hot chocolate/coffee machine in the waiting room! Everyone seems to think the place is great (it was recommended to me by my old English GP and gynae when I asked where I should go for CVS). The nuchal cost (inc blood test) about £130-150, can't quite remember. Not sure about the CVS. Well worth it, I thought.
Good luck!