Hi @MissMushy and welcome! I worked traditionally for years, but in 2015 I got an updated tablet and started practising properly with it. These days I often start off traditionally and finish a piece digitally.
I've seen this Slate advertised to me and had a look at it...seductive looking but ultimately it seems an expensive way to circumvent the scanner. Once you get to know Photoshop there are ways to separate out pen/pencil linework from the white background, from a scanned image, and then you can work on it digitally as you wish. Maybe it's good for people who are on the move, or don't have scanner access when working, I don't know. I also looked at the reviews and if I remember correctly, some people weren't happy with the reliability - so I'd check out the reviews of people who've tried it, before deciding.
There's another method you could use if you still want to sketch on paper - take a snapshot of your sketch with your phone, then send it to whichever device you want to draw with digitally. Then you can adjust the levels (if it's a bit dark), then colour/sketch/paint on top.
Some advice would depend on what digital device/software you want to use after your traditional sketch is done, because you can then work out a good workflow to suit that method.
Many people here are really enthusiastic about using the iPad Pro with the Procreate app for digital sketching, though of course that's more expensive, there are cheaper options too. Personally I still use a tablet with my desktop, and the tablet was not that expensive to buy (compared to an iPad Pro or a Cintiq, for example) so that's another way of trying digital without spending too much.
But don't feel you HAVE to go digital - there are so many good things about traditional working too, you can be professional in either method, just depends where you want to go personally