The moment I went vegan I couldn't in good conscience wear any leather or animal products. I found some old canvas shoes my father wore (and he's a size smaller) and I wore them for a month until I saved enough to replace my leather docs with vegan trainers.
However, you should do what you can do. Replacing a car's leather seats is much harder than being uncomfortable in your feet until you save the money to buy a pair of shoes.
However, in this day and age, it is much much easier to buy vegan clothes. Every major shoe brand sells non-leather shoes. You can now wear sneakers or canvas shoes to the office. Coats aren't only in furs, leather, or down. Socks and ties can be easily found without animal ingredients. Well, perhaps not ties as easily, but everything else.
Most of this is pretty easy. Stuff that is made from animals are: leathers (from any animal), wool (including cashmere, etc.), and silk. There's a few other things, but those are the vast majority. Most ingredients are listed in labels for footwear or clothing. A lot of stuff that may "look" like it has wool or leather is actually synthetic. Acrylics and polyesters and viscose and cotton and linens and polyvinyls and more can be used to to make nice suits, hats, insulated jackets, and more. Like I said, I don't think there is a major brand which doesn't have vegan friendly clothes in it.
...and if you go the used clothing route, it's also easy. It just takes time to get used to and some creativity in the beginning. But it's easy.
"The worker has the right to leave his boss, but can she do it? And if she does quit him, is it in order to lead a free life; where she will have no master but herself? No, she leaves to sell herself to another employer. She's driven by the same hunger. Thus the worker's liberty is only a theoretical freedom, lacking any means of realization; an utter falsehood."