Hi Vishal
first thing is to be clear on which version of the Approved document is relevant, I assume as your initial posting you are workin to the 2006 edition that applies to all work commencing on site after April 6 2007.
If this is the case the next thing is that the standard for fire doors in dwelling houses is FD20. The doors must be to a 20 minute fire resisting standard not 30 minutes, they do not need seals or to be self closing. I can quote the para numbers from ADB if you need.
Are your doors hand made for your house or are they available off the shelf? If so are they sold as having any fire resisting performance?
If they were made specially for you then the best approach would be contact a firm such as Envirograf- I believe the sponsors of this website are agents. They do a CD catalogue showing their products and a spec on how to use them, along with a video of an ad hoc fire test of a door upgraded using their products. There are other companies in the same field- and much advice from people like the ASDMA and Chilternfire.co.uk- formerly BMTRADA.
Oak and hardwoods generally perform better than softwoods in a fire- char rate is slower and char helps protect the wood beneath it. So irrespective of the detail of your doors, if the design matches, size for size one of the sample doors treated and submitted for test by such as envirograf - which will be pine- your door is bound to perform better. The tests are to 30 minutes and remember you only have to achieve 20 minutes.
Cant really help you with the door between kitchen dining room and hall, the staircase does need to be enclosed and protected from a fire in any room. Unless you go for sprinklers. It does not sound like your BCO will settle for less, such as a protected first floor landing leading to a choice of alternatve window exits via separate first floor rooms. I have used this before in difficult situations.