Here be Monsters!!!!
Actualy its just a few local venues that have sing arounds and such,and as far as I know no websites.
The Tap and Spile Grimsby Host an open mic night and an un-pluged accoustic night both on a tuesday Find the number in the phone book and give them a call.
This venue also boasts a variety of performers throughout the year and is well worth getting in touch with.

The Lads of Cara are often to be found deplorably intoxicated at the Brocklesby Hunt at Goxhill.
Music starts around 2100 each wednesday but if you get there earlier get on with it yourself.

The Six Bells at Barrow on Humber Has a back room into which on a Tuesday evening are crammed a huge and vastly tallented array of people who set to and play beautiful music all night.
They are a great bunch and make a great sound.

At the Old Cons club in Bargate Grimsby,a local group of Irish Music enthusiasts hold their band Practice in the main room downstairs from 1930 untill 2100.
Then anyone is welcome to join in or take a turn.
The band are mostly still wearing L plates but once the serious group practice is over there is a lot of fun to be had. So any one who likes to do a bit of tuition would be welcome too.