I think that History/Politics/CompSci/RS would probably be fine. Have a look at the websites for RG history departments to check what A level profiles they are looking for these days. Just pick a group of A level subjects you like and think you'll get good grades in.
Do you have any idea about the kind of history you would be interested in? Or the kind of law you would be interested in practicing? Obviously it is quite early days if you are doing your GCSEs. Your first focus should be on getting the best GCSE profile possible. The majority of people at the higher end of the league table for history will be getting mostly As and A*s at GCSE. You can always change your A level choices later.
Loughborough at number one