Not only is it NOT obligatory....it is completely unneccesary....so long as the proper services are done at the correct times by a VAT-registered garage.
I think the VAT registration is a way of showing that the work isn't done by your mate in his front drive.
Just a double check that it's a legitimate and qualified business.
Still don't see the relevance. Being VAT registered just indicates a turnover above a certain amount. It doesn't reflect on the skill and professionalism of the mechanic carrying out repairs/services.
All the above recommendations are absolutely true BUT; you've paid thousands of pounds for a new car and you're going to save a few pounds by having it serviced privately. Then you get a major problem and you expect the main dealer to treat you just like his regular customers. OK, he'll have to fix it eventually but he can put you at the bottom of his queue and mess you about. The guarantee period is limited; treat the extra cost as insurance.
It may not be obligatory but the resale value is going to be a lot less than if you have only used the main dealer for the services.
I would not get a new car serviced outside the main dealer.
also, s i found out with my merc, they have an electronic service history thingy now - no "stamp", so you need to make sure the garage used has the ability to do that too.