Don’t listen to that whole follow your heart stuff, being an MP and being in politics is all about how you play your cards, people you meet and relationships you build. The biggest mistake you can make is being too political, most MPs (even in their careers) don’t have much political activism, maybe once they began than jobs but certainly not before that. And in a digital world remember a lot of things you do are recorded and kept.
You want to be an open book so you can adapt to changes which are inevitable in politics. Holding strong views and being too politically active makes it harder to network, harder networking means less relationships, less relationships mean you ain’t gonna be someone’s ideal choice to stand in as a candidate.
Don’t base your party choices purely on ideology as that changes a lot, look at party culture and choose the party you think would motivate you BUT also one that you think would be happy to have you (consider their member base, types of people that vote for them, etc.). For example you might be left wing but you might be super posh, your poshness would hinder your success in the Labour Party, but an ideology can be faked if your career is in your best interest and you would thrive with conservatives in this case.