You have a very common car, it makes sense to buy a workshop manual,

I bet that there are even used workshop manuals on fleabay, in any event you should have one.

It sounds like a common problem (being common to all bulbs)so its likely

to be the brake light switch which is probably somewhere near the top of the brake pedal.

It cheaper to change it yourself (£6 to £10 than taking the car to a garage

Try a Google search for your problem and you will probably find several hints or even video on how to change it yourself.

Try a motorfactors eg eurocar parts ( use your registration number to identify your car) and look up the brake light switch to get an idea of the price, plus you can get it straight away using click & collect ( cheaper than turningup and asking)