Now is a brilliant time to restock your wardrobe as all the sales are on
Personally I would not be tempted to splurge all your money on a load of cheaper clothes.
If you've been buying particular brands from vinted & liked the quality etc I would carefully assess what you need to build the basis of a new wardrobe.
Somethings could give older items a new lease of life, giving you more time to continue building your your wardrobe up.
If you're in a position to keep saving, i would use the £700 for a winter / early spring wardrobe. And save to add summer items later.
As pp have said think about your actual life & what your most frequently worn clothes are.
Aim to have 5 or 6 day to day outfits that make you feel good when you put them on & that are suitable for your needs
2 x nicer outfits that you can mix & match to make outfits for daytime at weekends meeting friends, casual outings etc
2 x lovely outfits for nights out or special occasions
A couple of coats for differing situations including a wool one, a rain coat & a casual day to day jacket (puffa etc)
Good footwear - leather boots & nice trainers or shoes + a pair of boots or shoes for more special occasions
Bags / belts / scarves /jewellery / tighys / socks etc
You won't get all that with your money but you can certainly get well on the way
Good luck op, it's exciting to be able to buy a good few lovely things & it will make you feel so much better getting dressed every day