No there is no .co.uk drop service for .co.uk now since nametrack.co.uk stopped.
So you will have to catch the domains your self.
To find out when it drops :
"Nominet has a duty to contact the registrant of a DETAGGED domain name to confirm that they do not want to renew the domain name before it can be cancelled. This process can be time consuming, especially if the database holds poor quality contact information for the registrant. However, once the registrant has confirmed they no longer require the domain name, the registration will be suspended after 21 days and then cancelled between 6-8 weeks after that." nic.uk
Then I would suggest using
www.123-reg.co.uk to register it - because a) its the cheapest and b) its opensrs and instant