From the MG European website:-
Free roadside assistance for quick support in exceptional cases:
Year 1: Included
Year 2: Annual extension with complete vehicle maintenance by an official MG agent up to a maximum of 7 years.
MG offers pan-European roadside assistance and associated services (towing, on-site repair, transfer, secondary services,...) for all new vehicles sold by an official MG agent in Europe (excluding the UK), as long as you have your vehicle maintained by an official MG service centre.
I have extra, as a member of ADAC (Allgemeiner Deutscher Automobil-Club) and functions much the same as the RAC and AA.
I don't know why the UK is different to Europe but there it is.