As CR says the only way is seafreight in either a 20ft or 40 ft container. Not a big jump in price between 20 and 40.
A 40 about $4,000 USA to UK but you can get 3 light aircraft C150 / PA28 in a 40 foot. ( So get a couple of mates !!
Take the wings and tail off. With Cessna no problemo as you still have the wheels ! On Piper you will have to make a small dolly .
If its a US reg be careful going onto UK ! You will need an Export C.ofA. if is a private cat.
