Welcome Charlie. This site is a good place to start your BIR journey. We're a diverse bunch and we don't all hold the same opinions on certain things. I'm sure others will chip in and help out with their take on the answers to your questions.
1. Is it worth to buy Tikka, Tandori, Masala and other Patak's Paste that are aviable there ?
Some people dislike intensely the flavour imparted by these pastes and use alternatives. But many on here, including myself believe they do have a part to play in certain preparations used in BIR dishes. These pastes, or similar are in common use in restaurants and takeaways up and down the country.
2. I was thinking about Mustard oil is it safe to use it in the kitchen ? Cause i read that this oil is for external use only ;<
This is an EU labelling requirement. More information/discussion on this can be found by using the search facility on the site. The oil tends to be used sparingly, and mostly in marinades
3. Is it optional to use coconut flour instead of coconut block
Coconut flour is used regularly in BIR kitchens in dishes like ceylon and tikka masala. The block tends to be used when making a base sauce. Initially, I would follow this practice but that doesn't rule out a little experimentation

4. I was broswering through forum and i couldnt find easy/good chicken Tikka Masala Recipe (I will start from something thats easy) would you be so kind to give me any link ?
Probably the easiest to begin with before you try others and start to develop the dish to your own requirements / tastes
http://www.curry-recipes.co.uk/curry/index.php/topic,7662.0.htmland there is one guy on youtube i will give you guys link thats making chikken tikka masala takeaway style you think following this recipe will make good masala ?
https://www.youtube.com/watch?v=n1wjyOdNdSw
Julien has done loads of videos of dishes, preparations etc as well as two e books. There has been both postive and negative feedback. Check out the video section in the forum to see how other BIR chefs cook