I'm sure we have seen this Glaze before....English ? Continental ?

And i'm afraid i can read nothing on the base...nice glaze though !

Looks Belgian to me.

Agreed. Looks Belguim

Can we guess from where ?

Looks continental I agree , but the Staffordshire potteries also used a glaze known as tortoise shell which is a little similar .

Those colours were popular in the art nouveau period all over the place though.

Ive googled Belgian Pottery...base is very similar

Must agree the rustic look to jug is very typical of Belgian or Dutch pottery from the early 20th century. You often see these colours on pottery with a slight art nouveau accent be that a incised design, twisted handle or wider spout. The thickness of the clay and design normally points to it not being made by one of the best makers but more of daily use item from a local maker. Nothing wrong with that and probably more desirable for a modern UK Kitchen than one of the finer pots by someone like Klaas Mobach.