That post could really benefit from being broken into paragraphs. It's hard to pick out what you're saying, but as a guess, not taking Russian will not be the end of you. I actually think taking three language related courses may harm your future prospects, and so the variety that history will offer is good.
Anyway, your primary focus should be on obtainain 4 decent AS-levels for the time being, whatever they may be. But is there any reason why you can't just move colleges, you seem to have found one that offers Russian? Also, have you considered the possibility of taking a Russian AS-level next year, alongside your main 3 A-levels? Presumably your college wouldn't have a problem with that as you would be taking the 3 A-levels with them anyway. Plus you will still only be studying 4 subjects in any one year.
I think though, you're going to have to realise that as you progress, you need specialise. You're still thinking like a GCSE student. Currently you spend perhaps 4 hours a week on a subject? Next year it will be near 10, you should think about that. At degree level, you will spend 40 hours a week studying only one subject (or a hybrid of two at most).
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