FWIW I have an account with BUX Markets which you can use to trade CFDs/spreadbets. Platform is good, maybe not as feature rich as some of the bigger players, but it does the job. Spreadbetting is likely the best way to go for you as you pay no tax on gains, which means you keep more of your winnings and it removes the complexity of tax returns etc. One interesting side-benefit of the BUX platform is that they do not charge fees (beyond the spread) on positions where no leverage is used, so you can open a position in say the S&P500 and keep it open for a few years, then take any gains without having to pay CGT or other taxes - ie. it can be used to actually "invest" tax free. A bizarre loophole in our tax system.
Now having said all that, you will see this warning each time you login -
72.1% of retail investor accounts lose money when trading CFDs and spread bets with this provider - and you should heed that warning very seriously. As Gordon said above, you are statistically extremely likely to lose money if you use one of these platforms and if you're planning to actualy day trade, as it seems you are, I would bet the odds are significantly higher than that 72% figure.
As a cautionary tale, when I opened my account I said to myself I would use no leverage and would just use it as a tax free way of being exposed to the S&P500. Went great for a year or so, but then I opened a couple of fairly small positions with leverage (20:1) on Tesla and S&P500. They went very well because the market was really only going up, so I opened a couple more, then C19 came along and even though the market only dropped a small number of percentage point because of the leverage I quickly found my account at €0.
My tip would be to open an account with a regular stock broker (DeGiro say) and buy a couple of ETFs like the S&P500 and just leave it to make much better returns than you can make in your bank account. If you need to scratch the itch of 'trading' then only after you have these ETFs in-place so you can see what real investing looks like, open a BUX account and stick €500 in there and proceed to lose it