help required in understanding my next immediate step

[PJW]

1) How many modules do i need to sit in to gain 1.1.100 licence?

None!

The IRSE Exam is all about breadth of knowledge necessary for gaining full corporate membership of the Instituion; licensing is about being able to do the day job. Obviously there is some synergy, but actually completely independent since you can have a license without being a member of be a Member without a licence. Probably you should initially concentrate in getting a licence, but having said that starting to study for the exam is sensible even if it will be a year or two before ready to take it.

You'll find there is some information relating to the distinction under the Just Starting topic.

2)How do i choose exactly which modules to take? i.e. which of the modules are relevant to my needs considering im going for 1.1.100 license.

You must do mod 1 but not necessarily (and indeed PROBABLY NOT) first
Then 3 others.
Depends on the work you actually do but probably module 3 re Signalling Principles and module 5 re Signlling Applications.
By chance these are the ones we are doing at the London Study Group this year; we meet in Victoria area 17:00 - 19:00 on Tuesdays as a general rule. Details in the Study Group topic

3)If i pass the exam than i should be awarded the license right?

Totally wrong- see item 1.

However any study you do for IRSE Exam will be very useful to prove "underpinning knowledge" needed for the licence categories.

4)How long before i will be awarded this license, after passing the exam? and what steps are needed to be taken following that (if any).

As above, not relevant. To get a licence you need knowledge, training, experience, workplace assessment then your paperwork goes off to an independent assessor, obtain a temporary licence and then the formal licence.
Nothing to do with the exam.

5)What if i fail one module? do i have to wait until the next year (12 months) to sit in again?

Yes

6)Will i need to go through in-house assessment of some sort? The company i work for is pretty small company (35-50 employees) and is not on the approved assessment agent list (or whatever its called). What are my options.

As 4, you do need to be workplace assessed and this is often by an in-house assessor. However such services can be brought in from another company- these are known as assessing agencies. Many of the larger orgainsiations are in the business of selling their services to outsiders as weell as being used in-house; there are also some independent consultants working in the field. Suggest you investigate from the IRSE's main websitre that has a link to the IRSE License scheme information.

7)The work that my company does kind of touches on the subject relevant to signal designing and reviewing. For example, we review other companies designs and layout etc but never prepare it for them. We look at them from electromagnetic compatibility (EMC) point of view. So, i am trying to extend my knowledge of the subject by going beyond the EMC aspect of their design. I think the best way is to study for this exam as that will no doubt help me gain more knowledge.

based on this then module 7 may be appropriate to you.
The whole idea of the exam is that it causes you to learn about elements of signal engineering with wich you are totally unfamiliar, but it is usually best to start with a module most aligned to what you already know.

8)I will appreciate if anyone has any experience of people coming from EMC background into this field.

Do look at the module 7 area of this website for some relevant info, and indeed put EMC in the search to see what comes up.
I work in an office on a major re-signalling project where there are 2 EMC engineers with a long history of working in rail but are not themselves signal engineers- however they have picked up a bit, just like we pick up a bit of their specialism.

Happy new year to you as well.
You may care to attend the YM AGM, half day seminar and Review of 2011 exam in a couple of weeks time- you do not need to have applied to be a member of the IRSE yet, but do register asap to reserve your place (details on website under Exam Reviews thread within the Exam and Exam Centres topic)