Please, can you tell me if all the covers are removable for washing (including the ones on the pushchair attachment). Also, are there any stores that stock these travel systems so I can see if it's the right one for me?
Well, the INTERNAL carrycot textiles are removable and washable - this is rather normal. About the seat unit, you CAN remove the fabrics but I wouldn't recommend washing them in a machine. I mean, there are eco-leather parts, and they might crack. Also, these cheaper prams are prone to fading, and the washing in the machine might help it get worse.
So, overall, the inside covers of the carrycot, YES. The seat unit covers, NO - here, only spot clean or hand wash should be applicable if you want to keep your stroller system in good condition.
Read more about stroller cleaning and maintenance to know more and inspire yourself as to how to clean your stroller effectively and relatively easily.
About the system itself, this is a Polish brand that is not widely available at stores everywhere. If there's no Riko brand seller around you, then you'll probably not see it IRL. The carrycot itself is quite nice and large, even if simple, but the seat, be aware of that, is quite small, narrow, and short, on this one. So it won't last you that well. To add to it, do count on this system to be quite large, heavy, and bulky after folding, so it will need a big car boot.