Katex your gas consumption sounds way over the odds - your meter could be running fast - I had one like that once - paid about £15 for a meter check and because the meter WAS faulty I got that £15 refunded + recalculation of last 2 quarters bills.
OR - your boiler may be old and inefficient - you might get some help with replacement - look here
Central Heating Grants Available to UK Homeowners (72.52.135.154)