[dboreham]

Not trying to be rude, but someone who is complaining about PCB turnaround time, but has also never soldered SMDs sounds odd. You need someone who knows what they're doing on staff. Either hire that person or become that person.

It's been a couple decades since I was involved in the H/W business, but there are usually tricks you can use to assemble even very fine pin-pitch devices in your kitchen. Heat gun, microscope, etc. I'm guessing there are 100 YouTube videos on this. Assemblers will tell you it needs ZYX special machine that only they have, but actually you can do it yourself, albeit slowly and with defects here and there.

Back when, there were decent PCB houses in the UK (up in the midlands typically, not near London). Perhaps they're all out of business now but you might go looking for one of them vs back and forth to Asia for prototypes.

Edit: a quick search suggests that there are many UK manufacturers still alive. E.g. [Forward, Newberry, Leicester, Stevenage]circuits.

[MobiusHorizons]

Can't plus one this enough. These skills are very achievable, and IMO are required for successfully building prototypes. Especially if you want to be able to salvage an experiment where a couple of mistakes were made, you may need to cut traces solder a few wires and possibly bodge some components on in order to validate the design before ordering the next iteration.