The EU engineer licensing regulations for aircraft being talked about are still in transition. See the NPA published by EASA 4 October on B2L and L licences:
EASA - Notices of Proposed Amendment (NPAs)
The previous EASA Opinion on this proposal (Opinion 2009-04) was rejected by the EASA Committee (comitology process) in 2010 as 'requiring simplification' (that makes a change!). This new NPA is EASA's response.
Until these new proposals become law, extant national arrangements on engineers remain in place, including those in the 'BGA fleet' including TMGs.
At least that's my understanding.
As regards TMG training, prior to the new EU ATO regulation coming into practical effect, again national extant arrangements remain in place including those within the orbit of the BGA, approved by the CAA. These are not 'commercial', being conducted through specified (non profit making) clubs.
E&OE