Ok, lets start with the basics: You are UK based so I am basing this upon that. painting suggestions with what you have will follow when i have sleep.
What you have is fine for now. All of the following are suggestions on how to save money in the long run:
Primer:
https://www.reddit.com/r/minipainting/comments/xto1mm/best_cheap_black_spray_paint_uk/
Check the above thread on reddit. It has UK local suggestions for inexpensive primers.
Mainline manufacturers upcharge sharply. GW is $15/20 bucks USD per can for what you can get at a $6 price point elsewhere. I'd imagine the same holds roughly true for UK brands. You can have perfectly good primer coverage from inexpensive automotive spray primers.
Paint:
As a suggestion for a brand you can get good quality paints from at a rate of 2-3 paints per 1 of GW, I'd suggest
Vallejo. Specifically
game color. You want to avoid air paints until you have more time with brush control. They are designed for air brushes, but you can brush-paint them too, in which case they are a thinner (runnier, in other parlance) paint to medium ratio.
Army painter CAN work, but their quality control is all over the place.
AK interactive is another good brand but slightly pricier.
https://elementgames.co.uk/hobby-and-scenery/vallejo-paints
Element has had decent reviews in terms of customer service, so I'd at least look at their website to look at options.
Brushes:
There are two schools in terms of brushes for painting miniatures:
Route 1: Buy cheap, use-abuse-lose, repeat. In essence, experiment with regular artist brushes (inexpensive ones) from your local big box or Amazon. The key here is to find the brush sizes you like to use the most. Then, once you have that information, you can buy large packs of inexpensive brushes from places like Amazon or (if you are ok with buying from China) Temu. Sometimes temu sells rebranded brushes from the bigger hobby names.
Yes, your brushes will develop curves, or stray bristles, or other oddities. But at the size of the packs you can buy (I buy 100 packs from Amazon) you can afford to use them until they degrade and then have replacements at the ready.
Route 2: Buy expensive, buy care products, invest the time, keep the good brushes well maintained.
If you like to batch paint this could be the less ideal method, but it involves quality and taking care of it. i'm talking high end brushes that cost $15-20 per, even if they are small detail brushes. Taking these, familiarizing yourself with care (There is such a thing as brush soap.) and then investing the time in using those care materials.