Depending on what subject you’re looking to study you might find they’ll offer you a place on a “Foundation” year (or Stage 0 as some courses call it) – designed to enable people such as yourself without formal qualifications to get over the entrance hurdle. Be warned than if this is what is offered then you might find that a significant proportion of just-left-school Stage 0 students are there not because they want to learn, but simply because they want to delay unemployment (or work) for another 12 months; you could be the only person on the course who actually wants to learn, which can make it hard to retain motivation.
However, as others have said – go for it if you can. Some of the best students that I’ve tutored have come in via a similar route as you, and have ended up with a First Class MEng degree.