Childrens Car Seats

As I mentioned yesterday, I took my brothers family to Stansted Airport yesterday. This involved putting my four and a half year old Nephews car seat into my car, for safety and Law. Well have you ever tried fitting the seatbelt around one of these car seats ? The diagram on this one is none to clear.
First you find out that the child seat won't fit under your cars headrest and have to remove it. Then as your wrapping your seatbelt around certain parts of the child seat, putting it into clips, then round the back, you find that your seatbelt has locked and won't pull out any further. This forces you to let it retracked back a bit, where it goes back through one of the holes you've threaded it through, and has now fallen down the back between the car seat and the child seat.
When you finally get the seatbelt round and plugged in, looking a bit like how the diagram looks, you feel that you need to jerk the child seat forward, and check that the car seatbelt is gonna lock the child seat in place, where it doesn't. So you undo it, and repeat the whole process again, and realise it was correct the first time.

Now with this child seat in place in the back of my car, and my weekly groceries requiring purchasing, I've been wondering ? Can I get away with parking in the Parent/Toddler section of Sainsbury's car park ? (my preferred choice of Supermarket).
Their car park is usually full when I go, and as a hetrosexual male with no children, and thankfully no disablity, it is a nightmare to find an empty parking space, because half of them are set aside for black welsh lesbians with one leg, and I have to park near the Petrol station.
Then when you find the last free space in the car park, as you go to swing in, you find some lazy person has left a trolley in it !

No.5