Is your host asking for the domain to be transferred to them or are they asking you to alter the Nameserver settings?
If it's the transfer to them, then be careful. There is no reason for a host to demand that a domain be transferred to them... this also means that they can charge you whatever they want in the future to renew the domain!
If it's the altering of the Nameservers, then unfortunately you made a bad choice in buying your domain from UK2.Net... it seems that they charge £1.21 per month for changing "DNS records on our nameservers, including the MX record for mail exchange or add more subdomains." Bit of a raw deal