An SR22 can do EGNH - LFML nonstop. An IFR routing
ESTRY DCT WAL Y53 NANTI L10 HON N859 SITET A34 KOVAK H20 DOMOD A3 NEV R31 MTL is 728nm and a VFR one would not be much different in distance.
LFML is H24 with Customs so no need to clear Customs anywhere.
If going VFR, you need the UK and French charts (for France, got for the 1:1M SIA ones) and draw a VFR route in the usual way, either OCAS or in France using the Class E routes which are generally FL065-115.
I will send you an email/pm with some URLs.
An excellent French flying site is
here