Climb the steps at the end of the car park to bring you to the canal towpath. There's a snack bar here, with outside seating and the obligatory doggy drinking bowl.
 Turn right to walk along the towpath with the Chelmer and Blackwater Navigation canal on your left. Cross over the canal at the Fall Road bridge and walk through the new housing estate to the perimeter road, Battle Rise. Turn left and walk along the road until the bend where a track continues straight on. You can choose to either continue on the track or take one of the paths on the right that go up to the sea wall path. 
Follow this path all the way around the basin - there are gazillions of birds making a right cacophany on your left, and views across the river to the harbour and Maldon on your right.
As you come around the path you arrive at a lock which you can walk across into Heybridge Basin. There you'll see the Old Ship pub in front of you (plentiful dog drinking bowls here too!), and to the right, you have The Lock cafe with outside seating where dogs are welcome. Amazing deserts and a whole range of local Tiptree jams and produce to buy. There's a takeaway window at the cafe but if you want to use the toilets you have to eat in (but, out). You could do worse than sit at a table overlooking the water enjoying a fancy lemonade and a key lime pie, or a cuppa and a cream tea for the privilege of a loo stop.
After lunch/snack continue up along the canal towpath a few hundred yards until you arrive back at the car park, making sure to look both sides of the path otherwise you may miss the unusual sight of an array of wild animals dotted around a local resident's garden. 
The whole walk is probably 45mins-1 hour, not including stops.