I would be more concerned by rust in the wheel arches or on any of the underneath of the car body. You can sort the rust out with a small metal grinding wheel, and then prime, sand and spray it, on the bodywork.

My worry is that it will spread quickly and cause dangerous damage ! I only need a run around for a year and bit . Thanks so much for the input from you all very grateful .

If it's only being used for a year or so and it's cheap, then I wouldn't worry about it. It's superficial rust. It's structural rust that you need to look for - along the sills, jacking points, suspension turrets e.t.c.

It'll add to it's character.

My worry is that it will spread quickly and cause dangerous damage ! I only need a run around for a year and bit . Thanks so much for the input from you all very grateful .

If the car runs and drives well there is little chance that a bit of rust would become serious in the assumned remaining lifespan of the vehicle unless there are gaping rust-holes now. So if its nice and cheap dont worry.