Hello everyone - here's a recipe Ive found, although havent tried it personally:
(taken from Favourite country wines and cordials by Carol Wilson)
Sloe Gin

Sloes
Granulated sugar
Gin

Sloes are best picked after they have been frosted to get the juice flowing. Once picked, put in the freezer overnight for the same effect.
Prick each sloe with a darning needle. Half fill sterilsed bottles with the fruit. Add 30z suger to each 1lb sloes. Cover with gin, seal firmly and shake well to dissolve the sugar. Keep in a warm place and shake each day for several weeks. After 3months strain the liqueur through coffee filter papers into clean, sterilised bottles, seal well and leave to mature. More sugar can be added later if the liqueur is too sour. Improves with keeping.