£2200 sounds about right to me. Not a private radiologist or anything but from memory (and these were rough estimates a few years ago)
Plain film Chest X-Ray - About £100
CT scan of Head - About £400
MRI scan of same head - About £1000
Cardiac MRI is pretty specialised so you may find the people offering it few and far between and so the cost may be consequently pretty high
Sorry to disappoint but would be happy to be proved wrong