You can't cost share an N-reg in UK airspace, but an N-reg can be rented out OK (I checked it with the DfT myself).
I flew to Antwerp EBAW a couple of years ago. A very easy airport. It was apparent that with the "right methods" one could avoid the handling fee. It wasn't much anyway on the scale of flying costs but it would soon mount up if you were going there regularly.
You can avoid the handler's fee at a lot of airports by taxiing to the aeroclub. Obviously this needs a prior arrangement and you may have to join the aeroclub for this to work however
