Many people expect to walk into a classroom and, an hour later, walk out full of knowledge and ability. Almost like walking to a tap as an empty glass and walking out as a full one. Learning language is not like that.
Think of it more like going to the gym. You walk into the gym out of shape, unfit, flabby, wobbly. If you lie on the floor for an hour doing nothing you are going to walk out in the same shape. If you spend an hour working your heart out you will leave feeling tired and spent but you will still be out of shape, unfit, flabby, wobbly. However…if you spend an hour several times a week working out, working on your weaknesses, you will improve. You will be fitter, stronger, able to do more without tiring. The more you put into it the more you will get out of it. The more you work on your particular trouble spots the fitter and stronger you will become. The chances of you becoming a world champion are slim but the chances of you improving are 100%
Like the gym however, you need to keep at your language learning or you will slowly and steadily lose your fitness and become rusty. If you are one of the lucky few with muscle memory you may not end up at the level where you started but it does require regular training to keep your fitness.
The first step is the one to decide to get fit at your English. Then being motivated and dedicated enough to work actively and regularly at improving it. And prioritising it.
My suggestion would be that you begin with an hour a week for at least ten weeks. If you have time outside of this you can read articles and do exercises but the most important thing is the hour a week. Like going to the gym, the most important thing is your motivation and your will to improve.