There are mattress cleaning products out there, but with heavy blood staining you run the risk of making the matress to wet.
Best thing to do for heaviny blood stains is hire a company to come round and do a mattress clean for you. Probably going to be about �5 for a superking i should think.
But that is cheaper than having to buy a new mattress because either you got the mattress too wet and it goes mouldy and skanky, or you dont get the blood out and it goes skanky!
If you do an internet search you should find a few companies in your area.