I have clay soil which holds water today I have dug deep down in my borders and added horse manure to quicken the mixing prosess will it be a good idea to add blood worm or is it not worth it
Don't bother, the worms will come and do their job.
I agree with punkdoc, we are in a house built around 14 years ago and the garden suffers from the usual builders rubble, loads of clay and very poor soil.
The previous owners did nothing to improve things. We started whe we moved in just under three years ago. The area nearest our house when dug after we moved in had no signs of worms at all, totally devoid of life. We have slowly started improving things by adding better soils, manures etc.
When we dig near the house now we get tons of worms, even working their way into the areas of clay and rubbish we have not yet removed.
So as punkdoc says don't bother, save your cash for something else.