Don't get the Rx 550, you will barely be able to run anything very well. Try a Rx 580/590
For the same price for the mouse pad get the steel series QCK mass, best mouse pad on the market.
For CPU and motherboard go with Ryzen 5 2600 and a b450 motherboard
Get rid of that mouse and get a steel series rival series (they're all good)
For an SSD go with a Kingston 450 120gb, slightly more expensive (~£30) but higher quality and will last you longer.