Hello all
I've just bought my first slr camera- a Canon 550D
I live in South Africa where electronics are very expensive, and the exchange rate is really terrible, so my budget for lenses in incredibly small.
my main interest is in taking wildlife photos. There will be many times when I'll need a good zoom, but nothing too crazy.
I've been told by someone experienced that a good lens for me would be the Tarmon 70-200 F/2.8
I've looked into this lens, but I struggle to find one here in SA, and they are way out of my price range.

I've found these two second hand lenses:

Canon EF 55-250 IS f4-5.6
Tarmon AF70-300 F4-5.6

I can't find anythng with a lower f number. My camera already comes with the standard 18-55mm lens that most of them do, so I'm looking for something that will help me with zoom (and also animals are often on the move so this is a consideration)

I did initially want something that will still be good in low light situations, but I think I need to compromise because I cant find or afford anything with a small f.

Does anyone have any thoughts on which of the two options is best?
In your opinion would 55-250 or 70-300 be the right choice at F4-5.6 or is 18-135mm at 3.5-5.6 what i should be going for? I'm inclined to pick the 70-300 because I already have an 18-55mm and 70-300 seems to give me more options- is this the case?

All advice very welcome
thank you