As I understand it, you should really have the same tyres on the same axle, in other words the two fronts should be the same and the two rears the same, but front and rears can be different. I think that tread pattern is more important than brand but, as far as I have seen, no two brands seem to have the same tread patterns! You might need to be assertive with Kwik Fit though as they might try to palm you off with something else.