You can buy parts for any sets from UK DS broadly speaking. Parts from exclusives for US stores may be an exception, but you can always try; I think I have in the past.
There is no limit. I have had orders for £200 plus (largely parts for a number of other people, not just for me!) I email my order in using my own designed order form. However, what I have found is that dealing with a large order is very time consuming when you come to check the parts received as the order of parts on the invoice aren't the same as on your order. I also feel that long orders (and I base this partly on my own experience in running a data prep department) are more prone to error, although just why is unclear but it is certainly partly the result of a greater chance of the operator being interrupted and their concentration being broken while processing a big order compared with a smaller one. As orders from £30.01 are free delivery, I prefer to send in smaller orders (usually no more than 2 or 3 A4 pages) which will be more than £30.01. This way I get free delivery and less risk of errors in processing the order. Sort your order into ascending numerical part number order, btw. This helps the ladies doing the processing and, therefore, also makes for greater accuracy. (Having said a lot about accuracy, I do find that the staff at UK DS are very accurate and helpful, but if I can help them, then I do.)
