Paving Slabs around a pond?

Bed them on a mix of 3 course sand to 1 cement, fill the pond with water first to take up the slack of the pond liner.

 

Id get a seperate bag of cement and a couple of bagsof coarse sand, ie plastering sand.
It will work out cheaper, bring the liner over the edge, lay about 35/50mm bed of sand and cement then tap the slabs down to level with a rubber mallet.

 

Only thing to watch is that if using cement mortar to bed the slabs make sure none falls into the water and that the water doesn't come into contact with it, cos fresh mortar will raise the ph level and make it very unpleasant for fish.  Obviously not a problem if you aren't having fish in the pond...

You can buy concrete sealer from specialist pond suppliers such as Bradshaws to apply to the mortar when it is dry which will stop it leaching into the water.

 

If you want it to be nice & stable you really need to cast a concrete collar foundation 6-8" deep all the way around, as wide as the slabs, and lay the paving across that, liner tucked under about 1/3 of way.

 

That's the general idea. Although it will depend on how solid the ground is around the pond in the first place. Ie: if it's made from soil recently excavated from the pond itself, then it won't be very compacted and you can anticipate a lot of movement there - expect the slabs to move over time.

You're going to need a lot more concrete than you seemingly imagine, so using these ready-mixed bags will prove costly. Best, as said above, to buy separate aggregate amd cement for the 'founds' and sand for the mortar for bedding the slabs.