The official rules can be found on this page and that one.

The government announced yesterday that rules are going to be relaxed soon for people fully vaccinated (i.e. with a booster or two jag and a recovery certificate) but it is not yet published.

According to your status, you would need a less than 24 h PCR or antigen test. I can't tell how strong the rules are enforced. That certainly vary depending on the transportation method (car, train, plane...) but I have no doubt that there are more people unchecked than checked.

End of March is far. We switched many times between optimism et new variants and waves so anything can change before your arrival.

The official rules can be found on this page and that one.

Il convient de relever que tout voyageur entrant sur le territoire français en provenance d’un pays extérieur à l’espace européen doit présenter un test PCR ou antigénique négatif de moins de 48 heures. Pour les voyageurs non vaccinés en provenance du Royaume-Uni, le délai de réalisation du test PCR ou antigénique est de 24 heures.

Any person aged 12 and over entering French territory must present a negative PCR or antigen test less than 24 or 48 hours old, depending on the country of origin.

The government announced yesterday that rules are going to be relaxed soon for people fully vaccinated (i.e. with a booster or two jabs and a recovery certificate) but it is not yet published.

According to your status, you would need a less than 24 h old PCR or antigen test. I can't tell how strong the rules are enforced. That certainly vary depending on the transportation method (car, train, plane...) but I have no doubt that there are more people unchecked than checked.

End of March is far. We switched many times between optimism (the current trend) and pessimism (new variants and waves) so anything can change before your arrival. Some media start to talk about a possible end of the pass vaccinal by the end of March.