Hugo...

1 - ensure you have a working smoke alarm in the room with a dryer, they have multiple thermal cutouts but lint has a low ignition point.

2 - belts go over the drum on all except the costly miele, a sudden ba-ba-da in place of ba-ba-ba is a giveaway the belt is fraying.

3 - replacing motor is often not too bad, but the cost along with pulley tensioner can bump up the cost.

4 - replacing the rear sintered bearing can be quite involved (they can collapse, although not that common) and the shaft can be damaged.

Check YouTube for a video of your machine.
Sometimes eSpares or similar have a video about belt replacement, it is much easier with a video - a tedious job without.

Condensor are not cheap, unfortunately otherwise it might be easier to go buy new. Alternative is see what the manufacturer will charge for a flat fee repair? They might be £70 or £90 which is better than £350 for a new m/c. The warranty might be poor tho - 180 days in some cases.