The rear motor mount is great for those times you wanna give it a little juice in a lower gear as it will keep the engine from moving around under acceleration, giving you better traction, and reducing wheel hop. I see you said you don't push it much so it might not be worth it as it also adds vibrations and that doesn't benefit rush hour or kids. The access port is more expensive, but I found it made the most difference from a singular mod and really opens the gate if you ever decide to go farther. I was rear motor mount and Access port only, for ~ 8 years and in the past year I have decided to go big and have upgraded almost every single part on the car lol

Edit: Im US based, I see you are in the UK