Been using Single Bet Calculator for the best part of a year, mainly on mobile, so this is just my two pence. Stumbled on it through a Reddit thread, not an ad.
The slots side is pretty big — somewhere north of 3,000 games last time I counted. Play'n GO stuff dominates, so Book of Dead and all the standards are all there. I tend to live on Yggdrasil stuff out of pure habit. The one thing that irks me — Single Bet Calculator's search bar is genuinely poor, filters half work.
Live tables are Evolution-run, which is fine by me. Actual dealers, the stream holds up on 4G, and Crazy Time is where I lose most of my money, honestly. Should mention the UK tables are properly staffed in the evenings. Before you deposit anything it's worth a look at single calculator bet since the offers shift about.
Bonus-wise at Single Bet Calculator was ?100 matched plus 100 spins on Book of Dead. Playthrough sits at 40x which is about par these days. There was a ?5 no deposit token when I registered. Minimum is a tenner, sign-up took me maybe five minutes, KYC took a day.
Cashouts are decent. Visa and Mastercard are the slow ones, Skrill came through in under 12 hours, and crypto clears fastest. Took out about ?250 recently with no drama. The live chat on Single Bet Calculator took ten minutes once, three another time — human, not a bot script. Licence is UKGC, so at least there's a complaints route. No standalone app, just the mobile site.