You can get a painting kit for £21.50 it comes with Paint, 3 Miniatures and a starter brush and you got a choice of 4 armies to choose from 2 From AOS and 2 from 40K heres alink to the oe I got.
I got this box and it had a raised plastic for the omega, is that just this box then? https://www.amazon.com/Games-Workshop-Warhammer-Marines-Intercessors/dp/B08FFTT143/ref=sr_1_2?crid=3U5ONAESWNDYC&keywords=space+marine+paint+kit&qid=1661222629&sprefix=space+marine+paint+ki%2Caps%2C166&sr=8-2
I saw this which includes a few minis and stuff to paint it with. I haven’t gotten into the hobby yet but I’ve been playing Dawn of War and figured I’d check some stuff out. I’d mostly be in it for the painting rather than battling.
https://www.amazon.com/Games-Workshop-Warhammer-000-Intercessor/dp/B08FFTT143
Id actually recommend the ultra marine starter set that GW sells. They are better quality paint. And the brush is a nice bonus. You also get some test models to practice with. Youll of course want some additional paints, red for the eyes, a better gold for the metallic maybe even a brown for the leather.
But if you want to get some really nice paint, Vallejo is my go to brand for any and all acrlyic paints. These set comes with a nice variety of paints that will work for ultra marines and more. If you really want the specific blue, you can get a pot of macragge blue from GW. Vallejo is Great quality, and the droppers are soooo much better than the GW pods. You can also buy a cheap yet reliable hobby cutter. These thing are a life saver and worth their weight in gold.
Marvel United was also my first foray into Miniature painting. I watched several videos about techniques and things first, personally I used the videos by the YouTube channel Black Magic Craft but find whatever works for you, you might even find some specific Marvel United painting guides at this point.
I then purchased one of the Warhammer starter sets that comes with a few models, some Citadel paints and a starter brush, like this one: https://www.amazon.co.uk/Games-Workshop-Warhammer-Marines-Intercessor/dp/B08FFTT143/ though that's not the exact one I got.
That way I had a few paints and a brush to get started and a few models that I didn't care about to practice on first. I started by working on these sacrificial models just to get a feel for how much paint to use, how to layer, how to hold and use the brush etc, and then once I had done those and was happy with my progress, I bought more brushes and paints, a model holder etc and started on my Marvel United figures.
These are some of my work - https://i.redd.it/ddh2zfncazv71.jpg
There's always Amazon, but the prices are guaranteed to be jacked up and you'll still have to wait.