flue?

the simple answer is that u can't do anything, u will need to get a plumber involved as this will mean either moving the existing boiler or fitting a new boiler, even a new boiler may have to be moved anyway if the flue doesn't comply with the manifacturers instructions, i would also suggest that your boiler model is more than 10 years old anyway so a replacement would save u money on gas & should prevent costly breakdowns that u may get with your old boiler.
Don't 4get anyone that works on your boiler will need to be gas safe reg (not corgi reg) this changed 1st april 2009.

Keith Gillyon Plumbing, Heating & Building Services. (southampton).
May 2009

where is the flue going now

b
May 2009