IMO, 4 a levels plus an EPQ is too much to handle. It's better to focus on getting good grades in your 4 a levels than to have to worry about that
and an EPQ.
Does the EPQ truly benefit you? Kind of and kind of not (for me, at least) Skills wise, yes. It gave me useful researching, independent study, time management, planning and presentation skills, and made my life easier when I was doing other coursework cos I already knew how to reference and find academic journals.
Getting a university place wise, not really, no. Most top unis don't look at EPQs, although it might be a good talking point for an Oxbridge interview if you're doing an EPQ in something related to what you want to do at uni, plus it'll show that you already have these key independent study skills etc.
Some universities will give you a lower offer if you get an A at EPQ, it'll usually be one grade lower offer. You'll be able to see which unis take EPQ into account on their website but off the top of my head, there's Southampton, Birmingham, Queen Mary, Royal Holloway and probably a couple others.
I think it's important to do an EPQ in something you're really passionate about, otherwise you're going to lack that motivation to complete it. I'd do some research on potential topics, maybe sign up to do an EPQ but if after doing some research, you realise you can't think of anything you'd want to do it on or your workload is getting too much then you can always drop it later.
Hope that helps