Hi,
As per above, you'll need to research the type of car you'd like and evaluate the costs of ownership and running it of which part of it will be insurance costs and Car Tax discs (often referred to as road tax). The cost of insurance can vary enormously depending on a whole range of factors, age, postcode, make/model/type of car, overnight garaged or street parked, driving history/UK license holder .. and so forth.
It essentially comes down to how deep your pockets are and only you know that! so, before going out to buy a car, do evaluate what you'd like, and check on insurance costs first. Perhaps then you can either re-evaluate the type of car you want and create a shortlist of various makes/models to see which one suits you the best in order to then purchase.
Cheers, DtM! West London & Slough UK!