lLes stéréotypes à propos de mon pays

C’est un stéréotype que la cuisines anglaise mangont le mal nourriturest mauvaise.

Most natural way to say it
"mal" is an adverb, it means "bad" in a mostly moral sense
"mauvais" is an adjective, it's "bad" in the sense "of poor quality"

Maintenant, j’habite en France et je pense que c’est vrai parfois vrai.

Le qualité du pain c’est plus pire en Angleterre normalement, au lieu dehabituellement plus mauvaise en Angleterre, mais ici, il y a toujours des petites boulangeries faisant/qui faisaont ledu bon pain.

"of poorer quality", "more disgusting" is often "plus mauvais". Anyway, "pire" already means "worse", so you can't say "plus pire" for the same reason "more worse" is incorrect
"au lieu de" works with a noun. "Instead" alone is mostly "à la place", but here you'd need to specify a bit. "mais ici" is honestly the shortest and best way to phrase it
Either "faisant" or "qui font"

J’aime bien lea pâtisserie de Francfrançaise et je pense que, 'en Angleterre, on essaye de répliqucopier l’'éclair au chocolat et lea tarte citron, mais pas très bien.

"les éclairs au chocolat et les tartes au citron" would be better, stylistically speaking but what you've written isn't wrong in itself
Likewise, you may say "la pâtisserie" (as a concept, in general) or "les pâtisseries" (pastries as individual food types)

En revanche, il y a beaucoup due fromages, due viandes et des recettes traditionnelles quei sont moins connues.

"qui" is the subject relative pronoun. What (subject) is less known? Des recettes => QUI sont moins connues

Ces nourritures ne sont pas a la hauteur dvalent mieux que cela stéréotype.

"elles ne sont pas à la hauteur" means "they don't measure up". It means something is (metaphorically) too low to compare with a high standard
Since you actually mean the opposite, I wrote: "These sorts of food are worth more than this stereotype"
ce = this (as a demonstrative pronoun that is followed by another noun)
cela = that, that one (noun)