Posted: 14/07/2016 at 15:03
I have great clumps of grey and yellow clay in my soil and it was a nightmare to work for the first couple of years - but it's gradually getting there.
The best thing you can do for clay soil is to keep working it and to incorporate lots and lots of organic matter - rough textured or 'long' compost is good for clay. Digging breaks down clumps and the organic matter enriches and improves the texture. If you put in the work now you will have beautiful rich, moisture retentive soil within a couple of years.
If you have empty borders at the moment it's a perfect opportunity to do lots of soil improvement before you plant. Buy spent mushroom compost / composted farmyard manure / soil improver etc in bulk and spread it really thickly (6") over the borders and start digging it in. I have bought in literally truckloads of the stuff. If your garden is smaller you can buy this sort of thing by the cubic metre delivered in dumpy bags.
Personally - although it won't do any harm at all - I wouldn't bother adding grit except perhaps when you're planting bulbs or plants that need better drainage. I definitely wouldn't add sand (I have seen it suggested before) - that can make matters worse.
Finally I would second the suggestions to try to work with what you have. Enjoy being able to grow the clay lovers.