Can anyone follow Buddhism if the person has had drinks & ate non-veg in the past?

There are many types of Buddhists, with a wide range of faith and skill in the practice of the Buddha's teachings. Many Buddhist consume alcohol and eat meat. Buddhist are not expected to consume alcohol even though many Buddhist followers consume alcohol.

https://dhammawheel.com/viewtopic.php?f=13&t=18611&p=261588&hilit=

I believe the fact that the Buddha spent his efforts teaching the path to enlightenment to the world tells us that beginning on the path is possible for anyone who honestly wishes to do so. If it was not possible, he would not have bothered to teach us the way. The only requirement seems to be the desire to start on the path and do the work. To my knowledge, he never said that anyone who was honestly seeking enlightenment was blocked from achieving it by their past. Harder for some, perhaps, but no one blocked.

By your question, you seem to show that desire. So in a manner, you seem to have already taken the first steps on that path.

As for the best way to continue, I'd suggest it might depend on the type of person you are.

If you are a 'book person' who learns by reading and studying texts, reading the suttas published in many ways (including free on the internet) might be a good way to start. (Searching this exchange for 'best texts to learn from' might also be a good way to find effective sources.)

If you are not, seek out a local monk or teacher who has a reputation as an honest and effective individual others have learned from. Due to the widespread nature of Buddhism throughout the world, you probably can find one if you look hard enough.

Personally, (and this might be controversial to some), I would not worry, at this time in your search, about the type of Buddhist teacher (Mahayana vs. Theravada vs. ?) to seek out. Unless you already have some ideas as to which you are more attracted to, that nuance you can figure out later in your learning. In my humble opinion, it is more important that you begin your general learning of the Buddha's teachings; and, not let your concern about your past stop you.

Best wishes on your journey.

Seeing ones fault of the past (note that just eating meet is actually not harmful as long not active (by mind, speech, deeds) involved in killing, but of cause wishing or agree that beings are killed on ones desire after it, would have been), hearing the Dhamma of the Buddha, rejoicing on virtue, taking precepts, no matter how much wrong has been done in the past, wise people take refuge into the Tripple Gems (The Buddha, the Dhamma, the Sangha (the monastic Disciples)), and by doing so one is right on the change into another Ancestor-ship that leads upward and beyond. Just by this, if coming form pure heat, one has already grown to "be" one of the less saints in this world.

muditā

To take refuge by heart, based on joy in virtue and metta, is not at all a "beginner" step, but connected with much scarifies in the past to ever come so far and advanced Upanissaya (Paramis).

It's beloved to share the famous story of Angulimala, the serial killer in this relation.

Since not easy finding proper access for many, here also an opportunity for those in far outer-lands: Refuge and requesting Silas online.

[Note, not given for trade, exchange, stacks and other bonds in the world but for liberation]

Buddha taught "skillful means" or upaya-kaushalya, and the precept is about not killing animals for food. He said that if a monk was offered meat - that's okay. But to sacrifice an animal for the monk, he was refuse it. The general accepted practice is to never kill animals, buy meat, fish, poultry, or to prepare food with it. Not harming the animals and not supporting the harm of animals. Not all Buddhists do this, however. It is one of the precepts, but many lay followers only follow precepts for special occasions. Being a devotee, a servant to Buddha, is different and the precepts are followed. Like a monk (bhikku) or lay follower (upasaka). Or attending a retreat, pilgrimage, or similar situations. Alcohol is pretty much the same, but there's some distinction between consuming alcohol (5th precept) and being intoxicated/drunk. A drunk loses conscious control over their behavior, and is more severe that simply drinking a bit. Either way its against the precept. It is good to train ourselves in "skillful means" which reaps many benefits.

Yes. You can become a Buddhist, no matter what you were in the past.

In many schools of Buddhism, it is not compulsory to be a vegetarian, as long as the meat that you consume was dead (and usually frozen) long before you encountered it.

The first step is for you to understand the basics of Buddhism. You can learn the basics of Buddhism by reading the booklet "Without And Within" by Ajahn Jayasaro.

The second step is for you to take refuge in the Buddha, the Dhamma or Dharma (teachings of the Buddha) and the Sangha (the "ideal" monastic order of sincere enlightenment seekers). You don't need a ceremony for this. This is basically you deciding that you will trust the Buddha, the Dhamma and the Sangha to lead you on the path to freedom.

The third step is for you to voluntarily undertake the five precepts, which are basic training rules and not prohibitions. You undertake the five precepts because you believe that they are good for you, not because you're forced to. Refraining from alcohol and drugs is the fifth precept.

If you cannot perfectly fulfill the five precepts, it's okay, but you should try your best to stick to it. If you broke a precept, don't be remorseful - just endeavour to stick to the precepts next time.

The fourth step is for you to learn more deeply about virtues (sila) in Buddhism (including Right Speech, Right Action and Right Livelihood) and also try to follow them.

The fifth step is to deepen your Right View further, by studying the Dhamma (teachings) in detail. Please see this answer on how to proceed.

As long as a person gives up violence and drugs & alcohol, they can be a Buddhist.

The ideal step is to clearly see why violence & drugs/alcohol are harmful and do not bring happiness.

As for vegetarianism, it is not strictly Buddhist, even though it helps nurture compassion.