How is the faculty in universities in UK? I have heard that they are not very friendly and just give students raw points and go away. Is this true? Are the teachers helpful and willing to solve doubts and explain in depth during classes?
This is very difficult to answer without knowing the exact university and course as contact time and how that contact time is used can vary wildly, but I'll try to generalise.
In earlier years you will usually be spoon fed a bit more, with most classes having tutorials so you can happily ask questions and as the people doing tutorials/seminars are usually PhD students and Postdocs they have opted in to it (and been trained) so they're usually very helpful. In later years you will be expected to learn more independently as that skill is valued more than the knowledge you gain. So you might only have tutorials for one of your classes, and if you need something clarified you can ask them at the end of the lecture, in office hours, or via email, though you have to be somewhat careful with these options so as to avoid stopping other people from getting help. Generally you won't get to that stage though, things are usually very well explained and you will usually have your coursemates to help figure things out. Even in labs, if you're really struggling with a step then the administrators will help you with that step so you can continue the rest of the assessment, you'll just lose marks for not being able to do that one bit.
You should also get assigned a personal tutor who will be a professor in your department, they will/should help guide you through uni, signpost you to any resources in the uni which could help you, and talk with you and pass on any complaints you may have about the course, for example if a course is particularly bad.
I don't think many unis just give raw marks. At my uni you can only be awarded raw marks for non-final assessments, and as each module will generally consist of a final exam worth 80-100% of the entire module grade, this means that your marks are usually heavily filtered. In fact from what I've seen, the UK university assessment system is the most regulated in the world by a large margin as your final assessment is marked externally and the module syllabus must also be approved externally.