Can someone tell me how long it usually takes to ship to UK and what are the customs & duty like on bigger orders?

I have not ordered yet,but wondering what the time scales are for how long will it take to UK?

and also if you make bigger orders how does customs go for orders over the £135?

As theres so many things I wanna buy 😭but the internet states I will be slapped with a 20-30% customs fee and delivery fee so seems the cheaper route is buying individually to avoid this?