I am thinking of ordering my first unit but as I live in the northern UK, I have some questions.

First – the customs. I understand if I order custom-made unit there will be several weeks waiting time. But after it is sent, how about British customs holding time and extra charges (VAT and such)? You have some clients in the UK so I wonder how long it takes for unit to arrive from the day it was posted.

Also, because customised units have such long waiting time, I am thinking of getting a generic unit for my first time. How much influence I have on it? Can I send in hair sample for best generic unit colour match, or do I have to rely on colour numbers? My hair is rather tricky to classify, as it is dark blond in general, but some days it looks brown, others lighter blond.
I would also like to get some highlights of lighter shade on the unit - is it better to do it before ordering or when cutting it in at hair stylist?

Another thing is how much can generic unit be cut? At first sight, I pretty much have full head of hair so would need to shave the top off from temples, beyond the crown, but not much more cause my sides are rather thick, even quite high-up.