I need an isp with a good enough uplink to host around 20 servers on and a large amount of bandwidth.
also has to be uk based as i'm from the uk
well isp is not the problem, the problem is what Network the Data Center has. As it is impossible 2 host up to 20 servers at home, a Colocation service at a data center is needed.
Go for a rented server or co-location as the cost of getting redundant high speed pipes to your house will be far more than the rental for the rack space & bandwidth you need for 20 servers.