Yip, £150-300 is around the correct mark.... Its the amount of time a dental takes under GA that determines the cost.

A few weeks ago my cat got two teeth pulled and a scale and polish and it was £197.26....

There is really no alternative if a dental is needed, to save your cat ongoing pain...

Though vets are not keen to perform dentals on old cats (13 and over) or ill cats.

If you don't get the dental, and there is puss (indicating infection) a good course of antibotics (antirobe or Amp) will be needed to treat his bad gums... and anti-inflam injection given at regular periods. And repeat courses of AB's throughout his life.

My cats has gingivitis and he needs dentals nearly every year. So the fact your cat has bad gums means he will need regular dentals...sorry!