This is a first post to this forum but I would like to request some detailed advice

Our garden is in a heathland area near Bagshot Sand but the site was built up 10 years ago with 'soil' which has patches of rubble and even patches of builder's sand, but all very free draining and dry and the rain seems to skirt around this locality as well! There were few plants when we moved in, except struggling leylandii hedges, now removed and laurel hedges which grow well - those plants are tough

Recycled compost was used 2 years ago and neutralised stable compost last year and most plants have been chosen to withstand dry conditions; they still need watering from the butts in the dry parts of the year but are coping. Rhodedendrons have normal coloured leaves but a wisteria planted into compost in a bore hole through the 'scalpings' of the driveway needed sequestrene (are scalpings alkaline?)

The main problem is a long shallow sandy south aspect bank under two large neighbour's copper beeches which are immediately the other side of a fence backed up by privet. The beech roots run all through this bank and have reached the surface in places, so it is not practical to dig it over

What is the best compost to use annually as a mulch, especially on the bank, please? Is an additional general fertiliser recommended, when and which one please? Can you recommend an economy SE source for c.100 bags of mulch, when, and which one?

Available choices include the recycled Council recycled garden waste from the tip. A recent sample of something like this this looked dusty, seemed to dissolve fairly quickly, and smelled a bit like the tip so it is not favourite so far. The stable waste seemed nicer and certainly did not contain viable weed seeds but seemed rather light with what may have been straw, but persisted as a skin better. Non-peat composts seem to be available either with or without john innes and 'plant food'; they seem rather expensive, are they worth it, and which one? Bark mulch seems the most expensive, but is it best?

All advice and comments would be much appreciated