Hi - Which part of Suffolk are you in?...i'm just over the border in Norfolk.

Whilst i'm still in the process of designing my steel/aluminium build & am not as wise as many of the others round here, there are a couple of things that stand out to me.
I think you'll want to replace the middle side legs with 50mm box rather than the 20mm box.
The gantry looks to be uber chunky - the distance between the front of the gantry, the Y leadscrew & then the front Y plate all look far too big. It's also better to keep the Y leadscrew either behind the gantry or inside it to help keep gunk/chips away from it.

Good first draft though - much better than mine was