Early on they came with a granny charger or some had a type 2 cable. There should be a tyre inflator and there was a can of tyre sealant.
No locking wheel nuts as they weren't/aren't fitted with any from the factory.
That's about it. Mats were extra.
Ah... we all replied at once!
Note that a car handbook is not supplied - it is an online manual only, unless you print it off or buy from someone selling a printed copy.
Also, there's no service book. It is all electronic servicing so the records are held on MG's computers. An MG dealer should be able to print it off to give you a copy.
V2L adapter was always an optional extra.
There would have been a "Certificate of Conformance" in the glovebox originally, stating information about the car including manufacturing date. But these often go missing.
Some dealers supplied little credit card sized AA recovery cards giving details of the AA-recovery cover. This is included free if the car is serviced with an MG dealer (it is renewed for a year at each service).