What best to put in raised planters?

If you can get good top soil then go for that.

Thanks MG. Will try that then.

I've got two long raised beds Dan and I used top soil mainly but mixed some multi purpose and/or compost in the top 1/3 of it , quantities of half and half with the soil. Things seem to do well in this. as it absorbs and holds the water well. Mine are about 2'6" high and the level goes down a bit every year so I top up with either, whichever is to hand..

Be very careful to find a reputable company if you do decide to buy topsoil. We've had several members who have bought it - only to get pieces of Japanese Knotweed with the load - or even rubble and clay mixed in - obviously the 'spoil' from bulilding site somewhere!

So 'Buyer Beware'!

Take heed of what Spritz says!!! Topsoil is often a way for builders to make some money-on-the-side getting rid of waste soil. I've had many many rants on GoY about so-called top-soil! Thing is, to look at it, you don't know if you've got topsoil, subsoil or, as Spritz touches on, soil that contains weeds or, worse, pests that were not previously present.

You say your clay is not that great - are you sure about that? Clay soils can often be very rich in nutrients. The problem with them tends to be with the soil structure, which is very dense and therefore prone to compaction and poor drainage and dries hard. The way to combat this is to simply apple a large amount of organic matter, such as horse manure, which in time will vastly improve the soil's condition without all the risks associated wtih so-called topsoil.

I agree with the dire warnings about topsoil made by Spritz and Sid above - pay top dollar for graded topsoil from a good supplier, get the best grade, check it when its delivered - pick up a handful or three and squeeze it, then open your hand - if it's still friable, but not gritty and sandy, then it'll be okay, if its stuck together, it's clay and might even be subsoil (which usually looks a bit of an orangey colour). Riffle through it with a fork or something and see if its full of stones and weed roots - make the driver wait while you do this and don't sign for it until you've checked it. Get him to remove it if you don't like what you've got, and the only way that works is if you do a cash on delivery deal with someone, or half up front, half on delivery.
If you don't need too much topsoil, and can manage with a mixture of John Innes No. 2 and 3, plus some topsoil, garden centres sell graded topsoil in bags.