Agree with Vic. There are also the Italeri kits, which, although not perfect, are a much better fit than the Airfix versions. These are particularly useful in the earlier releases for the GR.1 and F.3 ( which is indeed longer, with a longer nose), and can often be found at reasonable prices on e-bay.
I picked up the earlier release of the GR.1 (first pic) a couple of years back for around £15.
The second pic shows the more recent re-release of the same kit, priced at around £38.