I swapped from omni to vegan coming up to 5 years ago.
I've found Koko milk to be the best for tea / coffee although I drink coffee black now. Alpro do a "growing up milk" which is slightly vanilla-y (like custard!) which is lovely in chai tea. Vitalite is the best butter sub IMO.
Avoid vegan cheese until you have forgotten what real cheese tastes like, although the Applewood one is reasonable.
A lot of substitutes are an expensive way to get something that tastes like the cheapest version - e.g. Violife slices taste like the cheapest type of 'cheddar' slice, Richmond sausages taste like school dinner sausages. You may have a more satisfying month doing meals that don't rely on them.
Not everything has to be a gourmet meal planned out with recipe books (unless that is your thing). Jacket potato with baked beans (other than Heinz no added sugar) is a decent vegan meal.
Tofoo smoked tofu is absolutely amazing and very versatile - you can mash it with vegan mayo for an 'egg mayo' filling for sandwiches or jacket potatoes, break it up with a fork and fry it for a scramble, add it to rice bowls, stick it in with rice and black beans and a tomatoey chipotle sauce, or just eat it out of the packet.
Barnivore is a good resource for finding out what alcohol is vegan (a lot of wines are made with fish finings).