FOB Shenzen means that they will deliver them in 7 days to Shenzen. You need to arrange a freight forwarding agent, and pay your own freight & Import duty. 6 weeks on a boat is useless so you would need to airfreight them. You can at least double the original cost for that. In other words....
don't bother!!
He's quite right, I deal with HK and Shenzen all the time through work. A forwarder from Shenzen would have to be arranged (don't worry, as I can use one of ours from work) it would be airfreighted and I would imagine this would cost up to ??150. An import duty would also have to be paid I would imagine - as there are probably numerous manufacturers based in Europe who could make the same product.
Also, you can't guarantee the quality of what you will get, and if it's crap they will just ignore you. You don't want to end up in the same situation as the Ashley Giles cups which all arrived with King of Spain on do you.
Go for a UK based manufacturer is possible, the unit cost may be higher, but the real cost is probably not a lot different.
If you're really interested, I can get the accurate cost for getting the goods in to the country from my forwaders - all I would need is the box dimensions and total weight.