How long will my new amazon account be subject to delay in funds availability?
At the moment my sales are held for 7 days after estimated delivery date and it's starting to build up.
A UK seller will be able to tell you, if you shipping with no tracking then the hold could be longer, here in the USA that is the new seller contract 7 day hold after delivery. I understand in the UK and Europe they can not do this after the account is established. If Amazon is true to form then your account should be released from investigation after 90 days trouble free selling.
Try making more orders and give it from 3 to 6 months. If your strategy is connected with more expensive items and fewer sales, you will have to list cheaper items so that you can increase the number of sales.