I'm going to try and play the garage plans off against each other as there are clearly differences between their own service plans and that from the MG portal. Perrys quote, for example, included the following per service:
S1: screen wash
S2: screen wash
pollen filter
brake fluid
key fob batteries
S3: same as S1
MOT
S4: screen wash
pollen filter
brake fluid
key fob batteries
transmission oil (?)
MOT
S5: same as S1
coolant change
MOT
Each service also includes a system check, software check and an aircon refresh. When you factor in a years worth of free AA Breakdown with each service, which currently costs £145 before discounts, it seems like a reasonable deal. However, the MG portal service plan is £150 less, I just need to extrapolate why.