Only my personal experience, but . . . . Unless you have a euro certificate of conformity (and obviously you don't) you'll have a hard time.
.....
Finally, if the DRIRE become involved, I'd just walk away.
Don't panic. The DRIRE can be very helpful.
The Certificate of Conformity makes it easy to import post 2002 bikes within Europe, as it proves that the bike is type approved, i.e. has gone through all new European road-worthiness tests. That doesn't mean that pre-2002 bikes cannot be imported, but the bikes will not have been subject to the same tests. The process below is the same in any event.
You need to obtain the Certificate of Conformity from the manufacturer's Homologation Department in the country you are importing to. The UK will happily supply you with a Certificate of Conformity for new BMWs, but when you come to present it at the Sous Prefecture, you may find that the homologation number (part of the VIN) is not recognised and you will find yourself back at square one.
When you contact the local HQ, the Homologation Department will ask you for a lot of details about bike, VIN no., tyre sizes, etc., etc. They will then tell you what modifications are required. You will probably need to have any work done by a main dealer as the department will need an authorised dealer's statement that the modifications have been done.
Assuming they are satisfied, the manufacturer will then issue either a Partial Certificate of Conformity or an Addendum to your UK Certificate of Conformity.
In addition to changing the headlight, Roynie had to have his UK-spec Triumph Tiger restricted to 71Kw (? not sure) to meet French standards. He was issued with a Partial Certificate of Conformity, and the modifications then had to be verified by the local DRIRE, who then sent the paperwork off to the Sous Prefecture on our behalf.
In the process of trying to register, firstly, the 1200 Trophy, then the Tiger, I had many conversations with the DRIRE in Toulouse and, apart from a certain exasperation over the unhelpfulness of Triumph's Paris office, the guy was polite and helpful. It isn't a particularly onerous process, but it does help if you are a fluent French-speaker, conversant with administrative jargon.