AFPEX DOES let you complete on p.c. and save a template as well as send it to them. I did it last week. Their 24 hr. help line folk are exceptionally helpful.
Alternatively the OLIVIA site, is very good for GA flight plans. English version and very user friendly. Even a once a year filer like me can find his way round it.
In the end they all work the same wherever you fly or file from.
Flight Plan via 'Olivier' available English option
OLIVIA
OR via the UK's AFPEX
https://ts1.flightplanningonline.co.uk/
BTW. To close flight plan in France, from anywhere in France call 0810537837.
And landing back in the UK close via UK 24 hour number for flight plans, 0845 6010483.
(It's also AFPEX' help line).
mike hallam