Withdrawal? Never got withdrawal from lack of meat, but then again, maybe I wasn't as hooked as you Now, if you mean cravings... well, suck it up, ride it out... and make sure you're getting enough protein from plant sources. That's about it.
Quorn based burgers, sausages, chicken substitute etc. Every large supermarket should have a range in their frozen food section. As Scratcho said some aren't so good so you just have to buy and try. I personally think that meat substitute products are not going to help with "withdrawals", better to change to a healthy vegetarian diet.
Make sure you combine plenty of non-animal protein from different sources to get all the essential amino acids.
when I first went veg, I had cravings that I eventually connected to FAT. I can't eat a lot of dairy, so I didn't load up on cheese like many of my generation and locales did. unfortunately, that was my fat source. I joke about my last hamburger, John Lennon was alive, but not for much longer. But hamburgers and fried fish were my fat sources (I was a kid in beef country, eating fish labeled me as a hippie commie). Dropped them, but didn't, oh, say, eat avocados or nuts. (seriously, it took me six months to see the light with peanut butter) The other craving source for me, and it is still a powerful connection, is a grill or smoker. The smell of woodfires, especially, as I grew up around families that barbecued goats for holidays and the fires burned from 3 am into the next night. that connection is hard for me to shake. But I don't get grossed out by the smells of cooking meat. It doesn't register as food, however. my fixes: ice cream (seriously) and learning to grill tofu and veggies.
there is a brand of false meat i like called 'yves'.. don't know if you have it where you live but it is pretty good and great for the transition for me. i used to be a complete meat eater so it was pretty difficult for me after a while. in the beginning i was simply having trouble eating meat without throwing up thinking of what i was sticking in my mouth! I've also heard lots about the brand 'boca'. if you see either of these, try them out