This is a situation where some calm thinking through of likely outcomes is a lot more productive than 'panicking'.
One scenario is that the outward flight is cancelled but your airline is still required to get you home.
They should have aircraft based in Europe that they can use instead so that might be an option especially if the weather isn't as bad later in the day.
If your flight is cancelled or significantly delayed you'll have to see what they offer.
They might say 'we'll bring you back on Monday', so then you just have to make arrangements re work, school etc.
If you're arriving in Manchester on Sunday afternoon or evening can you ask a friend or relative for an update about how your drive home will look and whether you should attempt it or get a hotel and go home Monday morning.
If they cancel the flight and totally abandon you, look up your rights and alternative ways of getting home.
Use Skyscanner to look at alternatives, even if indirect, but don't book anything against instructions from your airline as it will be harder to get your money back.
Hopefully you have a credit card or money to pay for any extra expenses until you are reimbursed by the airline or your insurers.
Good luck.