Replacing 4600 Tiagra STIs – any 10sp, post-mount hydro disc options?

So the Tiagra 4600 shifters on my commuter bike have decided that I accelerate too slowly – no longer fancy shifting up one gear at a time from gear 2. It’s definitely the shifter – you can see the indicator doing (see they have a use!)

Have tried flooding with GT85 which made no improvement so it looks like it’s time for new shifters 🙁

So I think the rear mech isn’t compatible with the new 4700 shifters which is what I’d probably go for (would like to have shifter cables under the bar tape as they get in the way of lights) so I’d have to buy a new mech as well.

So if I’m going to start off down that road, I’d quite like to go for hydro discs from cable as the BB5s on it are not as good as any other discs I’ve used. But I think the only 10 speed sti hydro brakes only come with flat mount calipers and my bike is post mount! 🙁

Don’t really want to spend tonnes of cash on it, so has anyone got any idea if there’s a reasonably economical way to move to hydro brakes while I’m replacing the levers, preferably with aero gear cables?