In Chinese, there's no such a thing "ask for a permission." It's a country with full of freedom! Chinese people are friendly and helpful. Just practice with them! Your skin is good enough to explain to them your Mandarin is so so. Body language is an international language! BTY, I can write you something useful in the restaurant: 服务员！ Waiter/Waitress! 绿茶 / 红茶 / 乌龙 / 花茶 / 随便 Green tea / Red tea / oolong / chrysanthemum tea / Anything 我要点菜。 I want to order. Then you need to invest a lot of energy into the name of the dishes. It's quite hard. 菜很好吃！ It's delicious! 埋单！ Pay the bill. I don't know what's the restaurant manner in the UK. As in Canada, people wait for the eye contact. But in China, everything need to be fast. So, when u r in a Chinese restaurant, raise your hand and SNAP! Then waiter or waitress will come to serve. If you want to find a language partner, try italki here. Or find an university student. Go to some event that young people will go. U just need to ask them: 你愿意与我练习汉语吗？ 我可以跟你交换英语。 People in restaurant and workshops are busy. And it's a policy that they can't talk to you when working or their boss will cut their salaries.

If you're liveing in China, just do not worry a little bit. Feel free to speak your Chinese out loud! Maybe your vocabulary is not enough to communicate well, maybe your grammar is laughable. Maybe your utterance would make your listeners confused. All these are not worth worrying.And you do not need to ask for permission in advance. Just speak out! What if you your interlocutors do not understand you well? Just change an expressing way and use your gestures! What if they laugh at your pronouncing, misuse of words or lack of suitable words, or poor grammar? You may laugh along with them! Remember, laughind does not definately mean unfriendliness. What's important is you're TALKING! And it's the way, the best and easist way to learn Chinese! When the listner finally get to know your intention, after they have laughed enough, the most likely thing is you'll learn the right way to express yourself in the certain situation. Actually, Chinese are friendly to foreigners, especially those who are learning and speaking Chinese, no matter how well or bad their Chiese is.

Just speak to them in Chinese! Some people won't reply to you in Chinese, but some will! Just keep trying and you'll find some people who will tolerate your learner Chinese. I used to work as a tour guide. My Chinese was awful back then, but there were plenty people who'd entertain me. Keep trying! You'll find the right people eventually! :)

I am a Chinese, My mother tongue is Chinese，and I want learning English.If you don't mind, you can add my WeChat "weikwer".

I think I can help you,just add me.