I am, tried a bit in the past but clover was too large growing, suspect it would be more successful drilling the cash crop in the autumn rather than the spring like I did@chester - did you / are you going ahead with this?
I am trying a bit this year. I put a mix of white clover & yellow trefoil in under spring wheat. I only did it for half a field, partly as it's expensive stuff and partly so I can see if there is a difference, in a fairly crude way.
I used this mix from Cotwold Seeds.
Happy to report back on how it goes if anyone is interested?