This is easily confused with the more common Milk Float from the Commer Construction Gift Set. The main difference is that the rear section is fixed and there is no device in the base for locking or unlocking that. It is, otherwise, the same thing with a white cab and chassis and light blue frame at the back with a plastic set of milk bottle trays and content.
This example is in good condition with some chips to the paintwork and signs of wear but it still looks attractive on display. The windows are clean and clear and it has good suspension and tyres. Because so many people had the Construction Sets, these did not sell that well as pre-made models and can be more difficult to find now.
Note that this did not come with the milkman character in the boxed issue.
There is a Co-op Van from a scarce set you could get with Co-op coupons. However the Co-op version had stickers and cast wheels and was actually issued much later in the 1970s. You may find some sellers confusing the two or even adding Co-op stickers to the 466 issue.