Keeping the gravel into check - Sean suggested gravel grids

After today's chat with Sean, I did a little research into the sourcing of some grids, for the front garden at 76 Victoria Road, as it will be used for bikes and wheelie bins. I like it to look nice but needs to be easy for the residents to take their bikes in and out.

I have found this on Ebay 

 Probably best to look on Ebay as this picture is very small.

 It works out at £8.50 if we by 16m2  I think we need 10m2 for the front of the house and not sure how much we need for in the back garden.