[Koha] Koha and British Library Z39.50

I am new to using KOHA and am trying to configure a z39.50 connection for British Library records as my library is using DDC and has many books from the UK. I contacted the BL and was told I need a special z39.50 client to import records as well as an account and that a web browser won't work. So my question is: is anyone importing records from the British Library? And if so what client are you using (mercury and marcedit were suggested)? Any help would be much appreciated. Ariel