There are flights from Paris to Perpignan. UK flights on budget airlines to Montpelier, Beziers, Perpignan, Toulouse and Girona (over the border in Spain- 1hr by car). Regular airlines fly to Toulouse, Barcelona, Marseilles.
TGV train from Paris, Montpelier or even Barcelona to Perpignan.
While a car is not absolutely necessary as there is the local regular bus which goes to Perpignan train station, but NOT Sundays, it is recommended in order to explore all the coastline hill towns as well as the rich, diverse Pyrenees area. There are many ancient cities and villages.