vw sharan won`t start?

I have a vw sharan 2l petrol s reg 98 that won`t start it is trying to but won`t.

I have changed the leads dizzy cap and arm plus plugs and the battery is ok.
I`m getting a spark and there is fuel but I`m begiining to think it could be the immobiliser.

after trying to turn the engine over I get a few faint beeps from the dashboard.

any ideas what could be wrong or how I could eliminate and or fix the immobiliser.

I have a solid key so no batteries to change

thanks in advance