Mate I wouldnt recommend sending your watch to a company like this unless you know them or you are prepared to lose your watch after paying them for the repair.
There are many places us UK guys could send our reps in the UK but there is a reason we dont, seriously dont consider this option unless you are certain that 1) you wont get scammed and 2) they will be able to repair it.
The site itself is dubious definitely a drop shipper products are low end reps at higher end price, certainly the ones I looked at quickly eg the fiddy.
If you lose that watch with them you got no hope of getting it back, none! Or your money.
This is just a bit of friendly advice mate and to be honest if your going to post it then why not just send it to Domi in Germany only be away a few days longer, no customs issues not expensive to post and hes a trusted guy on here!!
On top of that how will you explain getting scammed to your mate, cause if I was him I would expect you to cover the loss