Depending on where you live(which might initially be influenced by who you will be working for...) there aren't that many choices.
The lea will allocate schools based on catchment areas. Based on last year's results many of the popular schools were v oversubscribed therefore the catchment is quite small (0.4-1.3 miles are typical).
When you shop for your house you can ask what the catchment schools are. Or you can look on www.rightmove.co.uk. There's usually a link to everyhouse what the nearest schools are.
Having said that as your children won't be going through the selection process as per normal then you need to look at schools that may have spaces for your 2 and then get the house.
Within the central bit of Canterbury, the popular areas to live in are St stephens/St dunstans/Canterbury west station area where not only the fast trains depart to get to London under 1 hr but the nearest schools are St Peters Methodist (1 form intake = 30 kids per year), St stephens (3 form = 90 kids). The latter is not religious.
This is also near to the university of Kent so if those are your employers it's easy to walk or bus to work.
Blean and rough common are also v popular areas and they are within walkable distance to Blean primary (non religious). V good school. That's near to the university too.
This is typically referred to as north Canterbury. Private fee paying schools in this area include St edmunds, Kent college and kings (in the town centre; the junior school is in Sturry which is 3 miles outside Canterbury - about 10/15 min drive)
Then there's south canterbury. Typically referred to as the desired side (not sure why it's seen to be better? It's nice too but not sure why better). This is close to the hospital. People tend to try and get their children into bridge primary (3 form) or barham (1 form). Both are c of e. there's also the wincheap school and others like pilgrims way (which is in special measures). There is a fee paying school called St christophers. They pride themselves on having 100% pass rates in the Kent test (the grammar school test that people were talking about earlier).
This area is also near Christchurch university.
Lots of surrounding villages like littlebourne, bridge, wingham, Blean as mentioned earlier which have v good schools.
Because pfizer has just made about 3000 people redundant there is more movement than usual and attrition so you may have a better chance or choice of schools. Pfizer was in sandwich. So you may find lots of houses in that area for sale!
Good luck. Pm me if you want to discuss more. 