Hi Ian, are you using the existing posts or having to replace these too? If you are replacing the posts then I would definitely recommend you using slotted concrete posts rather than wood as this will extend the life of the fence considerably. The main thing is to keep the bottom edge of the fence panel clear of the soil by using a gravel board, supported with a centre stake. Useful Amtech tools for completing this task would be the adjustable post level P4875 and the trench shovel U1875. Use bags of post fix as this is easier than having to mix ballast & cement and just need to add water.