it will not be the brushes. They would cause the motor to stop running, or run intermittently.
If the noise occurs only when it is pumping out, at the end of each wash or rinse, start by opening the pump, in case there is a coin, bra wire, button or other item caught in it. To do this you pull down the "skirting" panel and you will see a round plastic cap rather like a jam jar lid, with a bar across to grip it. It might be seized and impossible to remove. You can use the little rubber tube to drain out residual water first. The manual will explain better (see link below).
If the machine jumps about and knocks and rattles badly during spinning, even with a light, well-balanced load, I should think it's the counterweights come loose. If you are handy you can take the top off and have a look inside. There are heavy blocks of concrete attached to the tub to reduce or prevent large movement. It might be that they can be refixed by a mender.
It doesn't sound to me like it is the drum bearings. You would usually notice specks of grease or metal particles on your laundry if that was worn out.
I don't know the relevance of the reduced ironing indicator. All that does is cause the drum to slowly tumble a number of times after it has finished spinning, to reduce creasing.
It usually costs in ther region of £60-£80 to have a local repairman come out, plus parts. Calling Bosch might be twice that, and if you do, see if they will offer you a twelve-month service contract which will cover another repair if needed.
But I would be thinking of getting a new one. The machine would be worth less than £100. www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=+Bosch+Classixx+1200+express&_sacat=71256
You can work out the actual age of the machine by looking for the "FD Nr." which means factory date. You can decode it by looking online. It might be visible round the rim of the door. The "E Nr" is a model number which a repairer will ask.
www.bosch-home.co.uk/customer-service/get-support/appliance-assistant
If it's included on the inventory of the house, you need to contact the owner.