Concrete blocks for shed base

[Bobbya82]

hi,

I want to to use some concrete blocks for a shed base and bed them into the ground.

Please could someone advise if the following would be suitable, resistant to frost and water?
http://www.wickes.co.uk/Wickes-Dense-Block-7-3-N-100mm/p/113505

Also what is the difference between the above and this, with one being medium?

http://www.wickes.co.uk/Wickes-Medium-Density-Block-7-3N-100mm-(B)/p/113504

Many thanks,

Pete

 

[Bobbya82]

Basically will they start falling apart over time? Any ideas welcome?

Thanks again.