The Causeway Coast Way is a truly great walk, taking in plenty of attractions and offering fabulous views. Much of it is off road, winding its way along beaches and cliffs. Great to hear you're coming over from Scotland to complete it!
Local transport is well geared up to cater for people doing the walk. There is a hop-on, hop-off bus that travels from Coleraine to Ballycastle, stopping off at many of the strategic places on the trail. The number of the bus is 402/172 and you will be able to download the timetable from: https://www.translink.co.uk
If you wish to commence the walk at Portstewart there is a local bus (number 140) that runs between Coleraine, Portstewart and Portrush.
Unfortunately I do not know of any companies locally that do luggage transfers apart from the likes of bespoke golf tours. Might you consider using local taxi services?
For more information about the area please take a look at our web site: https://www.visitcausewaycoastandglens.com
I hope you have a great trip and if we can be of any further help please let us know.